CHANGSHA - The death toll has climbed to 10 in Tuesday's gas explosion at a coal mine in central China's Hunan Province after investigators unveiled a cover-up.

The explosion happened early on Tuesday at Zubao Coal Mine in Lianyuan, a county-level city in Loudi.

Mine authorities reported on Tuesday that of the 29 people who were working in the pit, 16 escaped the shaft, nine died and four were rescued.

On Thursday, investigators from the city government of Loudi found one more miner had been killed in the blast, but was listed as "injured", the press office of the Loudi government said in a statement Saturday.

It said police had detained a manager of the mine surnamed Liu who was suspected of covering up the miner's death.

Three officials are under investigation, including two deputy mayors of Lianyuan and the local production safety chief.

Hunan Province has launched a two-week safety overhaul and suspended all small coal mines with annual production capacity of less than 300,000 tonnes.

Zubao Coal Mine is a small mine with an annual capacity of 90,000 tonnes.