DUJIANGYAN, China (AFP) - - The death toll from China's worst earthquake in over three decades climbed to nearly 10,000 on Tuesday with many thousands more trapped under crushed houses, schools and factories.

Rescuers were still struggling to reach towns and villages devastated by Monday's huge 7.8 magnitude quake in southwestern Sichuan province, which is still being pummeled by wave after wave of terrifying aftershocks.

More than 18 hours after the quake struck there was still little news out of Wenchuan country, a poor mountainous region of around 112,000 people situated at the epicenter.

China's state-run Xinhua news agency said nearly 10,000 had been killed, but the agency released a steady flow of grim news from towns across the quake zone which indicated the toll was expected to rise dramatically.

It said up to 5,000 people died in one Sichuan district, Beichuan, where 80 percent of buildings collapsed.

"Several thousand" were reported killed or buried in the nearby town of Hanwang after a factory collapsed, while over 600 people died and 2,300 were buried in Shifang city where there was a major chemical leak.

And over 60 corpses have so far been pulled out of the Juyan Middle School in Dujiangyan City, about 50 kilometres (30 miles) from the epicenter, where hundreds were feared buried.

Pictures posted on Chinese Internet news sites showed rescuers standing atop huge slabs of shattered concrete at the school as cranes tried to lift away massive chunks of rubble.

Some buried teenagers were struggling to break loose from underneath the ruins, while others were pinned under rubble and crying out for help. Grieving parents watched as cranes were excavating at the site.

"Several thousand" people were killed or buried in a southwestern China town where a major factory collapsed after a powerful earthquake, state-run Xinhua news agency said on Tuesday.

The report, which gave few other specifics on the casualty numbers, said the disaster occurred when a steam turbine factory collapsed Monday in the town of Hanwang in Mianzhu city.

Prime Minister Wen Jiabao warned the situation in the quake zone was severe as China mobilised its 2.3 million-strong armed forces to spearhead the search and rescue effort.

"The situation is worse than we previously estimated and we need more people here to help," Premier Wen said, speaking at the disaster relief headquarters in Dujiangyan.

President Hu Jintao urged an "all-out" effort to rescue victims and the authorities announced an initial allocation of 200 million yuan (29 million dollars) of relief funds.

World powers including the United States, the European Union, Russia and Japan rallied around China with sympathy and pledges of help.

"The thoughts and prayers of the American people are with the Chinese people, especially those directly affected. The United States stands ready to help in any way possible," President George W. Bush said in a statement.

The huge quake struck at 2.28 pm on Monday and rocked skyscrapers up to 1,800 kilometres (1,200 miles) away in cities across China and parts of Southeast Asia, where panicked residents fled into the streets.

The quake hit in the middle of the day when schools, factories and offices were full. While many buildings in larger cities withstood the impact, buildings in rural areas would not have been built to withstand such a large quake.

"I heard the vents ruffling and then started to feel the building shake and a couple of bits of the ceiling fell," Richard Morgan-Sanjurjo, a 30-year-old business consultant in Chengdu, provincial capital of Sichuan, told AFP.

"I ran so fast. I thought the building was going to come down on my head," he said.

The area had been rocked by more than 1,180 aftershocks of up to magnitude six as of 5:00 am on Tuesday, the Sichuan provincial seismological bureau said.

Relief forces were battling to reach the worst-hit areas of Wenchuan county approaching on foot, Xinhua said, as vehicles were not able to use the road littered with rocks and boulders.

All lines of communication were cut with the county, which is also home to the Wolong Nature Reserve, China's leading research and breeding base for endangered giant pandas.

But an official in Wenchuan managed to appeal for emergency aid via a satellite phone, Xinhua reported.

"We are in urgent need of tents, food, medicine and satellite communications equipment through air drop," Xinhua quoted Wang Bin, Communist Party secretary of the county, as saying.

"We also need medical workers to save the injured people here."

The health ministry dispatched emergency medical teams to Wenchuan and the Chinese Red Cross sent tents and quilts.

The quake's epicentre was about 93 kilometres from Chengdu, a city of more than 12 million people, and 260 kilometres from Chongqing and its 30 million population.

The death toll is the highest for a quake in China since 242,000 people perished when the northern city of Tangshan was flattened in 1976.

All trains to and from Chengdu were stopped on Monday, the city's airport was closed and planes diverted for engineers to assess the runways.

Trading in 66 listed companies based in southwestern China will be suspended from Tuesday after a massive earthquake with a magnitude of 7.8 rocked the region, the country's two exchanges said.