At least 75 people have been killed and 412 others injured after two earthquakes struck western China, local officials have said.

The tremors on Monday hit near the city of Dingxi in Gansu province, a region of mountains, desert and pastureland.

"More than 21,000 buildings were severely damaged and about 1,200 have collapsed," an official at the earthquake bureau in Gansu told the AFP news agency.

The deaths and injuries were reported in Min County and other rural southern parts of the municipality, Dingxi Mayor Tang Xiaoming told state broadcaster CCTV.

Tang said damage was worst in the counties of Zhang and Min, where scores of homes were damaged and telephone and electricity services knocked out.

The government's earthquake monitoring centre said that the initial quake had a magnitude of 6.6 and subsequent tremors included one of 5.6.

The US Geological Survey measured the magnitude of the initial quake as 5.9 and the depth at 10km. Initial measurements of an earthquake can vary widely, especially if different monitoring equipment is used.

Risk of landslides

The Chinese Red Cross said it was shipping 200 tents, 1,000 sets of household items, and 2,000 jackets to the area and sending teams from both Lanzhou and Beijing to help with relief work and assess further needs.

Heavy rain is expected in the area later in the week, raising the need for shelter and increasing the risk of further landslides.

Residents described shaking windows and swinging lights. Shaking was felt in the provincial capital of Lanzhou 177km north, and as far away as Xian, 400km to the east.

"You could see the chandeliers wobble and the windows vibrating and making noise, but there aren't any cracks in the walls. Shop assistants all poured out onto the streets when the shaking began," said a front desk clerk at the Wuyang Hotel in the Zhang County seat, about 40km from the epicentre.

China's worst earthquake in recent years was a 7.9-magnitude temblor that struck the southwestern province of Sichuan in 2008, leaving 90,000 people dead or missing.