US legislators have proposed a mine safety bill that would introduce tougher penalties for repeated safety violations.

The bill is expected to be introduced to the US House of Representatives within the week and would increase penalties for safety breaches and make it easier to shut down unsafe mines, according to the Associated Press.

The bill also includes provisions to grant further protection to safety whistleblowers and give mine inspectors the power to subpoena documents and testimony.

Democratic legislators consulted with the Labor Department and the Mine Safety and Health Administration to draft the bill, which senior Democrats say they want passed by the end of the year.

Changes to the mine safety regulations have been prompted by the explosion at Massey Energy’s Upper Big Branch coal mine in April, which claimed the lives of 29 workers.