A total of 21 people have been killed following the collapse of a roof at a coal mine in the Shaanxi province of northern China.

Close to 90 people were working underground in the mine when the accident happened on Saturday afternoon, reported state-run news agency Xinhua.

Initially, 19 miners were reported to have died, but rescuers found two more bodies trapped inside the mine on Sunday.

Meanwhile, 66 miners were airlifted to safety from the mine, which is operated by Baiji Mining. Authorities are investigating the cause of the accident.

Accidents are frequent in the country’s mining industry, where the safety record is poor despite the government’s efforts to improve miners’ working conditions and actions to curb operations of illegal mines.

In December 2018, seven miners were killed and three were injured in an accident at a coal mine in the south western part of China.

In October, 21 miners were killed following a pressure inside a mine at Shandong province that caused breaking of rocks, which ultimately led to tunnel blockage and trapping of workers. One miner was rescued alive in this accident.

China’s National Coal Mine Safety Administration reported 375 deaths in coal mining accidents in 2017, which is reduction of 28.7% from 2016.

“19 miners were reported to have died, but rescuers found two more bodies trapped inside the mine on Sunday.”

At a coalmine safety conference held in January 2018, the administration said that despite improvements, “the situation of coal mine safety production is still grim”.

China is the largest coal producer in the world. Its production of raw coal in November 2018 grew 4.5% to 320 million tonnes from the corresponding period of the earlier year.

In the first 11 months of 2018, the coal production increased 5.4% to 3.21 billion tonnes as against the same period of 2017, reported Xinhua.

In November 2018, China witnessed a 13.1% decline in imports year-on-year as against an 8.5% growth in October 2018.