According to the Associated Press, estate administrators Jeffrey Skeens (son of victim Grover Skeens), Carolyn Davis (widow of Charles Davis) and Owen Davis (father of Cory Davis) filed suit in US District Court in Beckley, West Virginia.

It is also claimed that about eight other families are still awaiting payments from Alpha, which took over Massey and all of its operational holdings in June 2011.

The families are asking for district judge Irene Berger to enforce the outline of the $US210 million agreement that the producer came to with the Department of Justice in December 2011 that allowed for $46.5 million in restitution to the families of the 29 workers killed in the blast.

The unprecedented agreement also included $34.8 million to resolve outstanding citations, violations and orders, and a $48 million trust to fund research and development projects for the improvement of miner health and safety.

Another $80 million was earmarked for investments over the next two years to add safety measures at legacy Massey mines and Alpha mines, such as ongoing safety skills and compliance training, the construction of a state-of-the-art safety training facility and the development and placement of “next-generation” mine safety equipment.

Also according to the complaint, all three families agreed to confidential settlements for wrongful death suits filed with Massey before Alpha acquired it.

Alpha was not a party to the agreements, and the families have said their additional restitution rights were never surrendered.

“Nowhere in the non-prosecution agreement does it state that because the defendants had settled wrongful death claims ... that no additional restitution would be paid,” the complaint said, with the plaintiffs noting that they were not privy to DoJ settlement discussions.

Alpha spokesman Ted Pile told the AP that the company had fully complied with the deal, including payouts to victims’ families, and that the three plaintiffs were “not due any additional payments”

In fact, he told the news service, the suit was the second from the families claiming entitlement to more money.

“Their original lawsuit was dismissed, without prejudice, by a US District Court judge this past May,” he said.

"So the plaintiffs' lawyers decided to file a new complaint asking for additional compensation once again. Alpha believes the new complaint continues to lack merit and we fully intend to defend this matter again.”

No hearing dates have been scheduled.