The agency said the individuals submitted complaints that they were discriminated against in the form of suspensions, layoffs discharges and other actions.

It also said a record 34 complaints were filed by the department in 2012 that alleged mine safety discrimination.

MSHA’s data revealed the filing of 101 temporary reinstatement requests from 2009 to 2012, an average 34 annually. It is versus an average of six per year in 1993 to 2008.

It also filed a total of 105 discrimination complaints with the commission between 2009 and 2012, compared to 63 during the prior four-year period.

“MSHA urges miners to exercise their rights and actively participate in monitoring safety and health conditions,” Assistant Secretary of Labor for Mine Safety and Health Joseph Main said.

“We take these rights under the Mine Act very seriously and will vigorously investigate all discrimination complaints.”

Section 105(c) of the Federal Mine Safety and Health Act of 1977, better known as the Mine Act, outlined that a miner cannot be “discharged, discriminated against or interfered with in the exercise of statutory rights because he or she has engaged in a protected activity such as filing a complaint alleging a health or safety violation, or refusing to work under unsafe or unhealthy conditions”

Additionally, the act mandated that should federal officials find a miner’s complaint was “not frivolously brought”, it would ask the commission on behalf of the miner to order immediate reinstatement while the individual’s case was pending.

Issues related to discrimination and retaliation of miners came to light at congressional hearings related to the Upper Big Branch mine disaster, where testimony was given that some miners were reluctant to complain about safety conditions due to fear of retaliation.

MSHA obtained similar evidence in its investigation into the causes of the mine explosion.