A powerful aftershock rocked southwest China's Sichuan province on Sunday, one day after a 6.1-magnitude earthquake left at least 28 people dead and about 350 injured, state media reported.

The aftershock, with a magnitude of 5.6, struck the area near the city of Panzhihua, the same region hit by Saturday's deadly quake, the US Geological Survey said.

Rescue teams rushed to bring tents, food and water to survivors, as well as to help evacuate more than 30,000 people from Panzhihua after up to 300 aftershocks rattled the area, the official Xinhua news agency said.

The area is southwest of the region devastated by a massive earthquake in May that left nearly 88,000 people dead or missing.

Twenty people were confirmed dead in Huili county outside Panzhiahua following Saturday's quake, while three were killed in the city itself and five more died in Yunnan province to the south, according to Xinhua.

Up to 10 reservoirs in the region sustained damages, as did several major roads, rail links and power lines, it added.

As many as 130,000 homes were damaged or collapsed in Yunnan province, while over 38,000 residences were damaged in Panzhihua, Xinhua said.

The epicentre of Saturday's quake, which struck around 4:30pm, was about 30 km southeast of Panzhihua, near Sichuan's border with Yunnan, according to the US Geological Survey. The quake was about 10 km deep.

Xinhua said 656 schools had been damaged and that heavy rain and difficult terrain were hampering rescue efforts, with mobile telephone communications patchy.

State television showed pictures of houses with large cracks in their sides, broken tiles on the road and people receiving medical attention under tents.