A 6.6-magnitude earthquake struck southwestern China on Monday, according to the US Geological Survey.

The quake hit around 43 kilometres (26 miles) southeast of the city of Kangding in Sichuan province at a depth of 10 kilometres, the USGS said.

There were no immediate reports of any casualties.

Tremors were felt in the nearby provincial capital Chengdu -- which is currently under a Covid-19 lockdown -- and the megacity of Chongqing, residents told AFP.

"I felt it quite strongly," a Chengdu resident surnamed Chen said. "Some of my neighbours on the ground floor said they felt it very clearly."

A resident of Chongqing said the quake was "pretty noticeable" and made the lights and furniture in his apartment shake.

Earthquakes are fairly common in China, especially in the country's seismically active southwest.

An 8.0-magnitude quake in 2008 in Sichuan's Wenchuan county cost tens of thousands of lives and caused enormous damage.

At least four people were killed and dozens more injured after two earthquakes hit southwestern China in June.

On that occasion, a shallow 6.1-magnitude quake hit a sparsely populated area about 100 kilometres west of Chengdu, the provincial capital of Sichuan with a population of 21 million.

It was followed three minutes later by a second quake of magnitude 4.5 in a nearby county where the deaths and injuries occurred.

Chengdu, a city of about 21 million people, on Sunday extended a lockdown imposed to curb a Covid outbreak.

The region has also suffered a summer of extreme weather, with a record-breaking heat wave noticeably drying rivers in Chongqing.