At least nine people were killed and more than 20 injured after a 5.5-magnitude earthquake struck Taxkorgan county in western China, the region's earthquake administration said.

The quake struck a remote mountainous area in China's Xinjiang region that borders Tajikistan, Afghanistan and Pakistan on Thursday morning.

The Xinjiang Earthquake Administration said 23 people had been injured, including one seriously, and more than 180 houses had collapsed in the lightly populated area.

The earthquake has affected more than 12,000 people, and about 9,200 people have been evacuated to safety, Xinhua news agency reported.

Most homes in the area are made of wood and mudbricks or rock, the agency said. Search and rescue work was under way, it added.

The US Geological Survey said the quake struck at a depth of 10km.

The People's Daily posted a photo on Twitter of a building in ruins.

At least 4 ppl dead after M5.5 quake hits Taxkorgan in northwest China's Xinjiang Thur morning: local hospital pic.twitter.com/WYS1BJrp89 — People's Daily,China (@PDChina) May 11, 2017

Other photos, all from the official earthquake monitoring centre, show ceiling panels on the ground in one building and products on the ground in a store.

Taxkorgan county has a population of around 33,000 and is notable for being a stop on the Karakoram Highway, built along the ancient Silk Road connecting China's far western city of Kashgar to the Pakistani capital of Islamabad.

The official Xinhua News Agency said there had been frequent aftershocks.

Earthquakes are common in China's west, although the low population density there often means casualty figures are low.

However, in 2003, a 6.8-magnitude quake in a nearby county killed 268 people.

China's deadliest earthquake this century, a 7.9 magnitude temblor with a depth of 19km, struck Sichuan province in May 2008, killing nearly 90,000 people.