More than 8,600 people died in the powerful earthquake that struck southwestern China on Monday, according to state media reports.

The quake, with a magnitude of 7.8, struck close to densely populated areas in Sichuan province, including the capital Chengdu, shortly before 2:30 pm (0630 GMT).

Xinhua news agency said 8,533 people had died in Sichuan on Monday, citing the local government.

The national disaster relief headquarters reported 48 killed in northwestern Gansu province, 50 in the municipality of Chongqing, 61 in Shaanxi province and one in southwestern Yunnan, according to Xinhua.

All of those provinces and Chongqing, a special municipality of more than 30 million people, border Sichuan.

Tallied together, Xinhua has reported the deaths of 8,693 people.

At least 30 people were killed in Wenchuan, the epicentre of the earthquake, Xinhua said, but added the number of deaths there was likely to rise as the rescuers had been unable to reach the county.

Roads leading to Wenchuan had been destroyed and storms had prevented military rescue helicopters from getting there, Xinhua and other state-media reports said.

In Sichuan's Beichuan county, which is close to Wenchuan, the number of deaths was estimated at more than 3,000, with 80 percent of the buildings there destroyed, according to Xinhua.

Xinhua reported earlier that 900 students were buried in the collapse of a high school building in Dujiangyan city, also in Sichuan.

Fifty people have been confirmed dead at that school, the news agency said.

Hundreds of people were also buried in two chemical plants in Shifang city, Sichuan, and more than 6,000 people nearby were evacuated, Xinhua said.