Nearly 10,000 people were killed in the earthquake that hammered southwest China, officials said on Tuesday.

Rescuers were still struggling to reach the worst-hit areas where many more may have died.

State media reports indicated the toll from China's worst earthquake in three decades was likely to soar, with Xinhua saying 10,000 people remained buried in the Mianzhu area of Sichuan province.

The Xinhua report did not make clear if some of those buried were included in the overall death toll.

Chinese Premier Wen Jiabao, who rushed to Sichuan, ordered roads to Wenchuan, a hilly area about 100 km (62 miles) from the provincial capital Chengdu that was completely cut off by Monday's 7.9 magnitude quake, to be opened by midday, Xinhua news agency said.

But rain and thick clouds meant that military helicopters dispatched to the area could not yet land, and if the weather remained overcast soldiers mobilsed to help with rescue work would try to parachute in.

In the Sichuan city of Dujiangyan -- about midway between Chengdu and the epicentre -- there were scenes of devastation, with buildings reduced to rubble and bodies in the streets, some only partially covered.

Troops and ambulances thronged the streets, and military trucks able to do heavy lifting had arrived. But many residents simply stood beside their wrecked homes, cradling possessions in their arms, and many huddled in relief tents under heavy rain.

'At least 60 or 70 old people lived there, as well as children,' said a hospital worker surnamed Huo, gesturing to a building in ruins. Mattresses and household objects could be seen poking through the rubble.

'How could they survive that?' she asked.

Rescuers had worked frantically through the night, pulling bodies from homes, schools, factories and hospitals demolished by the quake, which rolled from Sichuan across much of China.

In the same city, about 900 teenagers were buried under a collapsed three-storey school building. Premier Wen bowed three times in grief before some of the first 50 bodies pulled out, Xinhua reported.

'Not one minute can be wasted,' said Wen, a trained geologist. 'One minute, one second could mean a child's life.'    

Frantic relatives tried to push past a line of soldiers surrounding the school, desperate for news of their children.

'We're still pulling out people alive, but many, many have died,' said one medical worker.

At a second school in Dujiangyan, fewer than 100 of 420 students survived, Xinhua reported.

The initial tremor, which the US Geological Survey upgraded to magnitude 7.9 from 7.8, was followed by a series of aftershocks, which shook the area through the night.

'Some are still very strong,' said a Dujiangyan resident. 'We have put up tents outside to sleep in.'    

A group of about 15 British tourists were out of reach near the quake's epicentre, likely in Wolong, an area famous for its Giant Panda research centre, Xinnhua reported.

Sixty pandas at a reserve near Chengdu were safe, it said.

China's benchmark stock index traded down after the quake, which forced suspension of trading in the shares of 66 companies.

China's Communist Party leadership announced that coping with the devastating quake and ensuring that it did not threaten social stability were now the government's priorities.

'Time is life,' said an official announcement from the Communist Party Standing Committee. 'Make fighting the earthquake and rescue work the current top task.'    

The Sichuan quake was the worst to hit China since the 1976 Tangshan tremor in northeastern China where up to 300,000 died. Then, unlike now, the Communist Party kept a tight lid on information about the extent of the disaster. - Reuters