BOGOTA -(Dow Jones)- President Juan Manuel Santos said Thursday that he's ordering a full review of mining regulations and safety procedures following an explosion in an underground coal mine that killed 20 miners.

The explosion Wednesday at the La Preciosa mine was the latest in a string of deadly mining accidents in Colombia, and Santos called the rising number of mining-related fatalities unacceptable.

The blast was likely caused by a buildup of methane gas. Some 26 coal miners were inside, of whom 20 were killed and six were gravely injured.

The president, who has been in Europe all week on a trade and diplomatic mission, said he's decided to cut his trip short so he can return to Colombia and spend time with the families of the victims of Wednesday's disaster.

"Tomorrow I'm going to return to the country to be with the families of the victims," Santos said in a statement from Davos, Switzerland, where he is attending the World Economic Forum.

He said that upon his return, he will immediately order regulators to "review meticulously all the regulations and controls we have...because the number of dead in our mines is totally unacceptable."

Authorities estimate that nearly 100 miners died last year in various accidents, including a massive explosion at an underground coal mine in June in which 70 miners lost their lives.

Wednesday's blast occurred at the mountainous La Preciosa mine in the state of Norte de Santander. It's the same mine where an explosion in 2007 took the lives of 32 miners.

An official at the government's mining oversight institute, known as Ingeominas, said all but four of the miners' bodies have been pulled out of the mine. Concerns that there could be another explosion have hampered efforts at reaching the bodies still inside.

Colombia Mines and Energy Minister Carlos Rodado said Wednesday that the mine was legal and its paperwork was in order; still, the government is going to temporarily close the La Preciosa mine to perform an investigation. He said 10 mine safety experts from Chile were arriving shortly to assist.

Officials didn't indicate who owns the La Preciosa mine, except to say that it's locally owned.

Analysts said more government action is needed to reduce the possibility of future mine disasters.

"Just a few years ago more people were killed at the same mine and the authorities promised to clean it up," said analysts at Celfin Capital in Medellin. "Now it's time for someone to take the fall...it is crystal clear the authorities have not checked on the improvements promised."

Colombia ranks as one of the world's top coal exporters. Its production destined for abroad is controlled by foreign companies including Alabama-based Drummond Co., Glencore International AG, BHP Billiton Ltd. (BHP, BHP.AU) and Xstrata PLC (XTA.LN), which operate in open-pit coal mines. Small locally owned mining firms, meanwhile, continue to produce in underground mines, most of which have poor safety records.

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