The death toll due to a carbon monoxide leak inside a coal mine in southwest China has gone up to 23, while one person has been rescued, officials said on Sunday.

The accident took place at around 5 pm (local time) on Friday at the closed Diaoshuidong colliery in Yongchuan district of Chongqing Municipality.

The dead are among 24 people trapped underground by excessive levels of carbon monoxide gas at the coal mine, where they were dismantling equipment in a pit.

The mine was suspended and shut down over two months ago.

The cause of the accident is being further investigated, state-run Xinhua news agency reported on Sunday.

The Diaoshuidong coal mine, which was established in 1975 and became privately-owned in 1998, has an annual production capacity of 120,000 tonnes of coal, according to the local emergency management department.

In March 2013, hydrogen sulfide poisoning in the mine left three dead and two injured.

Though safety improvements have reduced deaths at coal mines in recent years, mining accidents are common in China, which is the world's largest coal producer.

At least 16 people died in late September after high levels of carbon monoxide trapped miners at the Songzao coal mine in Chongqing.

China, which is both the world's largest producer and consumer of coal, has now reported more than 100 coal mining accidents in 2020.

In November, the government launched a year-long review of all working coal mines and coal-mining projects, focusing on infrastructure, risk prevention management and capabilities for emergency response and rescue.

Coal production in China typically ramps up between November and February in order to meet production targets.