A town at the epicentre of China's deadly earthquake has suffered "unusually severe" damage, with more than 70 percent of roads damaged and all bridges destroyed, a top military commander said Tuesday.

Lieutenant General Li Shiming told state television that the town of Yingxiu was also suffering from perilously low supplies of food, water and medicine after the quake cut it off from the outside world.

"The situation in Yingxiu is unusually severe," Li said in an on-air interview.

It was believed to be the first on-the-ground information from the epicentre area.

Li spoke after a team of 1,300 army medics and troops had reached the area, located in quake-devastated Wenchuan county, in southeastern Sichuan province, earlier in the day by foot.

It was the first sizeable relief force known to have reached the area.

"Helicopters are prepared to airlift food, medicine, and water to the area once weather conditions allow," said Li, who gave no information on casualties or damage to buildings. It was not immediately clear whether Li was in Yingxiu.

The team had to hike in overland due to massive damage to roads in the region, Xinhua news agency reported.

Yingxiu has a population of 6,641, it said.