HANOI - Five coal miners have been killed after a mine in northern Vietnam collapsed, local authorities said on Tuesday.

The accident happened on Monday at a coal mine in Quang Ninh province, the country's largest coal mining area, the provincial People's Committee said in a statement.

The victims, all males aged between 23 and 47, were employees of a unit of state-owned coal miner Vinacomin, state media reports said on Tuesday. Vinacomin was not immediately available for comment on the incident.

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An investigation into the cause of the accident is underway, the provincial committee said.

Coal mining accidents are not uncommon in Vietnam, which remains heavily reliant on the fossil fuel for power generation. Coal-fired power plants accounted for 60 percent of the country's electricity output in the first half of this year.

In April, four coal miners were killed and seven others were injured in coal mine gas explosion at a mine run by another unit of Vinacomin.