Click here for dramatic new footage More than 50,000 people may have died in the earthquake that devastated parts of China on Monday, state media say.
The warning came after the government confirmed the death toll had risen to 19,500, as rescue efforts continue to search for thousands still trapped.
The town of Yingxiu in Wenchuan County
About 10 million people across Sichuan province have been directly affected by the 7.9 quake, state media said.
China is mobilising 30,000 extra troops to Sichuan to help the 50,000 already involved in rescue efforts.
China says it will accept foreign aid and has agreed to help from rescue teams from Japan and its rival Taiwan.
Survivors from Wenchuan County have had to flee the area on foot
Correspondents say the death toll, which rose from 14,866 on Wednesday, is expected to rise further as rescue workers dig more victims out of collapsed buildings.
People are still being pulled out alive - a three-year-old girl and a pregnant woman were both found alive on Wednesday.
Desperate search
The BBC's James Reynolds, in Hanwang, says rescuers and relatives of those trapped reject suggestions time has run out for finding survivors alive.
At Juyuan Middle School, near Dujiangyan about 50km (32 miles) from the epicentre, 900 children were trapped in the rubble. Parents frantically pull away the debris from the ruins.
"It's not that we don't trust the rescuers," local resident Deng Yuehong told Associated Press Television on Thursday.
Pregnant mother Zhang Xiaoyan was pulled alive from the rubble
"They have done a lot of work to search for survivors but they couldn't search all the places in such a large area here and there may be some places that they ignored.
"We just want to have another try to see if there are any bodies of school children buried here."
The Chinese government has appealed to the public to donate basic equipment to help in the rescue operation. It said hammers, cranes, shovels and rubber boats were urgently needed.
The health ministry says there will also be an increasing demand for medicines and sophisticated medical equipment as the rescue operations continue and survivors are treated for injuries such as bone fractures, crushed internal organs and kidney failure.
More than 10,000 medical workers, police and volunteers have been sent to Beichuan County, one of the hardest-hit areas in Sichuan province, where up to 5,000 are thought to have died.
Appeal
Deputy health minister Gao Qiang says more than 64,040 people have been treated since Monday's earthquake - 12,587 of them are seriously injured, Xinhua reports.
Officials say about 10 million people have been affected by the quake, many are in refugee camps, without proper shelter, food or clean water.
The International Federation of Red Cross and Red Crescent Societies have issued an emergency appeal for medical help, food, water and tents.
Gu Qinghui, a member of the Red Cross assessment team told AP television: "I just came back from Beichuan County this morning, basically the whole county has been destroyed, there is no Beichuan County anymore.
"No one knows what has happened in particular areas, in the villages. I am sure that the numbers (death tolls) will just go up continuing day by day."
Olympic tribute
Tonnes of aid has been dropped from aircraft into isolated or inaccessible places in the province.
China says its contributions to the relief effort, in both cash and goods to the quake-hit areas, had risen to 1.34bn yuan ($192m).
Members of the public have also donated millions of yuan in both cash and goods.
Organisers of the Beijing Olympics say a minute's silence will be held at each stage of the torch relay, which is making its way through China.
Donation points are being set up along the route. It was due to leave Jinggangshan in Jiangxi province on Thursday.
A girl is rescued from the rubble of Juyuan school in Dujiangyan
No damage has been reported to the massive Three Gorges Dam, also in Sichuan province, but there were concerns about dozens of smaller dams closer to the epicentre.
Sichuan's Vice-Governor Li Chengyun said incomplete figures suggested 14,463 people were dead, another 14,051 were missing, 25,788 were buried in the debris and 64,746 had been injured, Xinhua reports.
Officials reached the town of Yingxiu, in Wenchuan County, to find the devastation was worse than expected - out of the town's population of 10,000, only 2,300 have been found alive.
The head of a police unit sent into the disaster zone said the losses had been severe.
"Some towns basically have no houses left," Wang Yi, told Sichuan Online news site. "They have all been razed to the ground."
Two days on from China's most devastating earthquake for 30 years, the scale of the damage is just becoming clear
The BBC's Michael Bristow says there are collapsed buildings all along the road to the nearby city of Beichuan.
This picture shows the scale of the damage in one town alone in Beichuan county. Damaged or blocked roads mean rescuers have to dig through rubble with their bare hands.
Stadiums have been put to use to house the displaced.
Meteorologists are forecasting a small break in the poor weather that has hampered aid efforts.
Helicopters have now been able to fly into the quake zone to take food, drinking water and medicine to Yingxiu - one of the towns in the mountainous area where the quake was centred.
But the weather remains cloudy and more rain is expected at the end of the week, said the National Meteorological Centre.
Slow effort
China's Prime Minister Wen Jiabao has flown to the epicentre to see relief work, having met survivors elsewhere.
The government has despatched tens of thousands of soldiers to the region to dig any remaining survivors out of the rubble and bring food, medicine and drinking water to the survivors.
Roads in the mountainous area have been badly damaged by the earthquake or have been covered by landslides.
Many soldiers and rescue workers have been making their way to cut off areas by foot. Others have parachuted in or have arrived by helicopter.
Workers are digging through the rubble of collapsed buildings with their bare hands.
Rescue workers now say hope is beginning to run out for more than 1,000 people thought to be trapped in a collapsed school building in Juyuan township, near Dujiangyan.
----------------------------------------------------------------------------
Cries for help The quake - now upgraded to 7.9 magnitude - struck on Monday at 1428 local time (0628 GMT) and was felt as far away as Beijing and the Thai capital, Bangkok.
Strong aftershocks continued to shake the region on Tuesday - keeping nervous survivors from returning to their homes.
Boulders and landslides are blocking roads in the worst-hit areas and helicopters have been unable to land because of the bad weather.
Beijing has deployed 50,000 troops to help with relief efforts, but they have not yet all arrived.
The earthquake destroyed many roads
The 1,300 rescue troops and medics who reached Wenchuan county immediately started searching for survivors and treating the injured, Xinhua reported.
There is no word yet on casualty figures there. Previously the only contact with the area was when a senior government official appealed for outside help using a satellite phone.
In the nearby town of Mianzhu, 10,000 people remain buried and massive landslides have buried roads to outlying villages, Xinhua reported.
Across the region, schools, hospitals and chemical plants were all reported to have been affected.
There were harrowing reports from the scene of a school collapse in Dujiangyan city, where 900 students were buried and at least 50 killed.
Teenagers buried beneath the rubble of the three-storey Juyuan Middle School building struggled to break free, while others cried out for help.
Another of the worst-hit areas appears to be Beichuan county, about 50km from the epicentre.
Some 80% of buildings there were reported to have been destroyed, leaving between 3,000 and 5,000 people dead and up to 10,000 injured.
Another school collapsed there, leaving more than 1,000 students dead or buried, Xinhua said.
Meanwhile, hundreds of people were reported to have been buried in two collapsed chemical plants in Shifang in Sichuan.
More than 150 people were killed in the provinces of Gansu and Shaanxi, and in Chongqing municipality, Xinhua said.
And there are fears for the safety of staff, tourists - including a group of 15 British visitors - and the panda population at a giant panda research centre at Wolong in Wenchuan, which has not yet been contacted.
But 60 pandas at another breeding centre - in Chengdu - are reportedly safe.
Open response
US President George W Bush expressed condolences to victims' families, while the US, Britain, the European Union, Japan, South Korea and Taiwan reportedly offered aid.
"The Chinese government are to be commended for their quick and efficient response. The UK stands ready to assist," said British Foreign Secretary David Miliband.
It is China's worst quake since 1976 when 242,000 people were killed in Tangshan.
The BBC's Quentin Sommerville in Beijing says this is probably the most significant natural disaster to hit China in recent memory, but that the Chinese army has a good record of mobilising and getting people to safety.
He also says it is one of the most open and speedy responses to an emergency he has ever seen from Chinese state media.
The fact the quake was felt in Beijing, he says, means millions of people will feel connected to the disaster and will be watching TV screens closely to see how the government responds.
Source:
BBC NEWS
Previous Topic
Index
Makes The 
Go Round!