In a US Securities and Exchange Commission filing released last week, the producer said it was now facing lawsuits by four employees claiming injury or emotional distress as a result of the April 2010 blast.

Eight families of those killed in the explosion have settled with the company and five have been given court approval on their settlements.

Massey said in the SEC documentation that settlements to date totaled $US78 million, which it expected to recover through insurance.

The figure “represents our best estimate of the probable loss related to potential future litigation settlements associated with the UBB tragedy,” the company said.

“Given the uncertainty of the outcome of current investigations, including whether we become subject to possible civil penalties or enforcement actions, it is possible that the total costs incurred related to this tragedy could exceed our current estimates.”

Earlier this month, in a separate SEC filing, the company said it had offered the families of the dead miners settlements of $3 million.

Massey announced in January it would be acquired by Alpha Natural Resources. The deal is expected to close the same day as the settlement offer is reportedly set to expire, June 1.

Federal, state, company and independent investigations into the UBB blast are still ongoing.

The US Mine Safety and Health Administration has planned a gathering at its academy campus in Beaver, West Virginia on June 29 to brief the public on its findings.