TORONTO (miningweekly.com) - St Louis-based Arch Coal temporarily suspended production at its Dugout Canyon mine, in Carbon County, Utah, last week, after an increase in carbon monoxide levels was detected in a mined-out area, the firm said on Tuesday.

The mine was idled on April 29, after the "small increase" was detected in the area, which was in the process of being sealed.

No employees were injured and the mine was not damaged, the company said.

Arch, the second biggest coal miner in the US, believes the increase was caused by a 'hot spot' in a previously mined area. Carbon monoxide levels have not increased since the incident was first detected.

The company does not know when the mine will restart, and warned the issue is expected to take "several weeks" to resolve.

It is finalising plans to finish sealing the affected area and to allow it to flood with water.

For now, Dugout Canyon will ship coal from its inventory to meet contract commitments.

The mine accounted for around 2% of Arch's total production in the first quarter of this year, and employs 275 people.

Coal mine safety has become a hot-button issue in the US, after 29 people were killed in an explosion at a West Virginia mine owned by Massey Energy.

Massey, meanwhile, said on Tuesday it has asked a board committee led by director Richard Gabrys to examine Massey's track record on safety, facts related to the UBB tragedy and the related investigations by various agencies including the FBI.

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