TAIYUAN, May 6 (Xinhua) -- Rescuers have recovered the bodies of three more miners who were trapped in Saturday's gas explosion in a coal mine in Linfen, a city in central Shanxi province, north China, driving the confirmed death toll to 23.

The fate of seven other miners is not known yet as rescue efforts continue, according to rescue headquarters.

Zhao Tiechui, director of the State Administration for Coal Mine Safety Supervision, has asked the rescuers to focus on searching for the missing while making sure they themselves are safe.

"Rescue work is quite difficult since the shaft is still filled with smoke," said Zhao at the scene on Sunday.

"The smoke inside the shaft is so thick that it's very difficult for us to go down to look for those still trapped," said one rescuer.

The gas blast occurred around 1:50 p.m. on Saturday at Pudeng Coal Mine in Kecheng township of Puxian county where 125 miners were working.

Ninety-five miners, including 23 who were injured - one seriously, escaped, according to a press release given by Shanxi Provincial Bureau of Work Safety on Sunday.

Bureau sources said the coal mine had been earlier ordered to suspend production but mine operators resumed production on Friday without a permit.

"The coal mine was in a mess and under poor management," said the provincial work safety watchdog, adding that the 125 miners who were working underground at the time of the blast had been hired by five different mining contractors.

Zhao, together with local officials led by Shanxi Governor Yu Youjun, are at the site to supervise the rescue operation.

Local police have put the coal mine owner and several managers under surveillance.

Provincial officials have ordered an investigation into the explosion.

Pudeng Coal Mine, with an annual production capacity of 150,000tons, was set up in 1986 by a village and became a private venture in 2004.

The Pudeng explosion is the second colliery accident within six days in Shanxi, China's largest coal producing province.

On Monday, a blast in an illegal mine at Liujiacun village, Yuxian county, killed 14 people.

Two owners of the mine, both natives of Yuxian, fled after the accident, but their assets were soon frozen by police.

Shanxi boasts of coal reserves topping 264 billion tons, amounting to 26 percent of the national figure. It produces about 600 million tons of coal a year.