Alpha confirmed the lawsuit with a statement: "Going forward, we do not intend to pay any legal fees with regard to Don Blankenship's defence. In response, Mr Blankenship has now filed suit in Delaware against us."

The legal filing said Alpha's lawyers say the company determined Blankenship had reasonable cause to believe his conduct was unlawful.

The former Massey Energy CEO filed a lawsuit against the Bristol, Virginia-headquartered company Alpha, alleging the company recently told him it would not cover his costs to defend charges that he conspired to violate safety standards at West Virginia’s Upper Big Branch mine.

Blankenship, whose leadership of the giant coal conglomerate has been described as “iron fisted”, faces up to 31 years in prison having pleaded not guilty in court last November to raft of charges stemming from the tragedy, including conspiracy, fraud and making false statements.

He was released on a $US5 million cash bond with travel restrictions after pleading not guilty.

A federal grand jury returned the 43-page indictment against Blankenship in November alleging that he took short cuts on safety to maximise profits, including failing to properly ventilate the mine, in the lead-up to the explosion at the Upper Big Branch mine in April 2010.

Investigators believe a build-up of methane and coal dust caused the deadly blast.

His attorney William Taylor said in November that Blankenship “is entirely innocent of these charges” and was adamant he would be acquitted, indicating he was only indicted as he spoke out against powerful figures.

“Don Blankenship has been a tireless advocate for mine safety,” the lawyer said in a statement.

“His outspoken criticism of powerful bureaucrats has earned this. He will not yield to their effort to silence him. He will not be intimidated.”

In an ongoing saga, Blankenship’s attorneys filed for an extension to January 28, asking the judge to allow them two extra weeks to prepare their motion to transfer the case to another district. They cited prejudicial "pre-trial publicity" and an extensive number of media reports as the reason behind the request.

Prosecutors opposed the extension, arguing there is "no reason to conclude that two more weeks to collect news clippings will affect the court's analysis of a change-of-venue motion."

Judge Irene Berger ultimately granted the motion on February 4, allowing the defence until February 20 to file the motion to relocate the trial.