Jacques Rogge pledged China the support of the IOC after the southwestern part of the country was hit by an earthquake Monday. (Chung Sung-Jun/Getty Images)

Jacques Rogge pledged the support of the International Olympic Committee and the Olympic movement to China after an earthquake struck in the southwestern part of the country Monday.

More than 8,500 people died when a 7.8-magnitude earthquake hit in the Sichuan province, trapping adults and children under the rubble of collapsed schools and office buildings, and causing ammonia spills at a chemical plant, state news agency Xinhua said.

Rogge, president of the IOC, wrote a letter to Chinese President Hu Jintao on hearing media reports about the earthquake and offered the IOC's support.

"We send our deepest-felt condolences for the victims. The Olympic Movement is at your side, especially during these difficult moments. Our thoughts are with you," Rogge said in the letter.

Xinhua, citing government officials, said 8,533 people died in the Sichuan province alone, while another 10,000 could be injured. In one county of Sichuan — Beichuan — an estimated 80 per cent of buildings were reduced to rubble.

The earthquake, felt as far away as Pakistan, Thailand and Vietnam, struck about 100 kilometres northwest of the Sichuan provincial capital of Chengdu, the U.S. Geological Survey said on its website. It hit at 2:28 p.m. local time, when schools were full and office buildings were packed.

People were also killed in the provinces of Gansu and Yunnan, and the municipality of Chongquing.

"This appears to be a major disaster, the scale of which is only just becoming apparent. I feel deeply for those affected and join in solidarity with the people of China," Rogge commented later in the day upon hearing of the reported rising death toll.

Beijing is scheduled to host the Summer Olympics from Aug. 8-24.