Beijing - China's housing ministry on Friday said it had ordered local authorities to investigate why so many school buildings collapsed in Monday's earthquake in the south-western province of Sichuan.

The order followed the destruction of 6,898 school buildings among the 216,000 structures that reportedly collapsed in Sichuan, ministry official Han Jin told the official Xinhua news agency.

More than 2,000 children were buried under rubble at just four Sichuan schools close to the epicentre of the 7.8-magnitude quake.

"If quality problems do exist in the school buildings, we will deal with the persons responsible strictly with no toleration and give the public a satisfying answer," Han told the agency.

Casualties at the collapsed schools were relatively high because the quake hit at 2:28 p. m. on Monday when most students were in class, he said.

At least 1,000 children and teachers were buried under the main building of Sichuan's Beichuan Middle School, after the seven-storey structure collapsed into a pile of rubble about 2 metres high, the agency said.

Another 900 children were missing at the middle school of nearby Juyuan township, and 200 were buried at two schools in Hanwang township, reports said.

Five primary school children were confirmed dead and more than 100 were injured at two schools in Liangping county, in Sichuan's neighbouring region of Chongqing.

Allegations of poor quality construction and official corruption in the building of schools are widespread in many poorer inland areas of China, such as Sichuan and Chongqing. (dpa)