SHANGHAI (REUTERS) - A county in south-western China has ordered a halt to shale gas mining amid fears it may have helped cause an earthquake in the area that killed two people, state news agency Xinhua reported.

The magnitude 4.9 quake hit Rongxian county in Sichuan province on Monday (Feb 25) afternoon, damaging thousands of buildings, injuring 12 people and affecting more than 13,000 people, Xinhua said.

It was the third earthquake above magnitude 4 to strike the area in two days, Xinhua said late on Monday. It cited experts as saying the earthquakes might have occurred due to natural causes, "but they could not rule out industrial mining".

"Due to safety reasons and requirements on safe production, shale gas mining companies have suspended mining work," it quoted the county government as saying.

Rongxian county is part of the region known as the Weirong block where state oil and gas firm Sinopec Corp is drilling for shale gas.

Weirong is Sinopec's second main shale discovery after its flagship Fuling project in the Chongqing municipality, which is located in the same geological basin of Sichuan.

Sinopec declined to comment.

PetroChina, which also operates in the nearby Weiyuan block, said in an email to Reuters that "due to safety reasons and production safety requirements, the shale gas development enterprises have suspended their operations upon communication with PetroChina Southwest Oil and Gas Field Branch."

The company did not provide further details.

Citing experts from the Sichuan provincial earthquake bureau, local state media reported earlier on Tuesday that it could not be ascertained whether the quakes in Rongxian were related to industrial mining activity.

Meanwhile, the state-run Global Times said five quakes had hit the area since January including two on Monday above magnitude 4, prompting "some residents" to gather outside the government's offices to call for a halt to shale gas exploitation.

The newspaper cited video footage on social media showing more than 1,000 people attempting to topple the gate of the government building with some 100 police trying to keep the gate upright. Reuters has not independently verified the footage.

"Some residents came this afternoon after the earthquake, and now they have calmed down and left. Government officials have responded to their requests," the newspaper quoted a Rongxian county government official as saying.

China's state-owned energy companies were set to increase spending on domestic drilling this year to the highest levels since 2016, after Chinese President Xi Jinping called last August to boost domestic energy security.

Mountainous Sichuan is a hub for China's decade-long drive to tap shale gas, which makes up about 6 per cent of the country's total gas output.