(Reuters) - Twenty-three people died after being trapped in a mine in China's southwestern city of Chongqing, the official Xinhua news agency said on Saturday, the region's second such accident in just over two months.

The dead were among 24 people trapped underground by excessive levels of carbon monoxide gas at the Diaoshuidong coal mine, the agency said, adding that one survivor had been rescued, after more than 30 hours of search and rescue efforts.

Friday's incident, which occurred at about 5 p.m. (0900 GMT) in a mine shut for more than two months as the company dismantled underground equipment, is being investigated, it added.