After explosions in the Merrimack Valley revealed how susceptible Massachusetts gas infrastructure is to disaster, the pressure is on for National Grid to end it's months-long lockout of union gas line workers.

House Speaker Robert DeLeo joined the growing list of Massachusetts officials calling on National Grid to immediately end the three-month long lockout of gas workers Wednesday evening.

"It's important that both sides really continue to have some real meaningful conversations to bring resolution to whatever outstanding issues there are. But in the meantime, let's get the people back to work," DeLeo told WGBH News Thursday.

"My main concern when I'm talking about this whole thing now is public safety. And I think that because of that these people should be allowed to go back to work," DeLeo said.

DeLeo issued a statement backing Steelworkers Local 12003's right to return to work while negotiations continue on a new contract with National Grid.

“With the tragic occurrences in Merrimack Valley and as winter approaches, public safety demands that we have as many trained professionals as possible operating our natural gas transmission and distribution systems. Therefore, I am formally calling on National Grid to immediately end the lockout. Both National Grid and the Steelworkers Union should resume their negotiations as soon as possible and negotiate in good faith," DeLeo wrote.

In a response to DeLeo, National Grid said temporary workers brought on after the union's contract expired in June have worked safely without incident. The company did not agree to end the lockout, instead they'll meet with union negotiators September 25.

"The unions canceled our previously scheduled bargaining session for this week, but we are eager to return to the table for their next available date, Sept. 25. It’s important to note that since June 25, the unions have only met with us 10 times in 13 weeks, so we look forward to a more aggressive schedule that will give us the opportunity to work collaboratively on all public safety-related issues," National Grid spokesman Christine Milligan wrote in a statement.

DeLeo is the latest in a long and bipartisan list of state officials calling for an end to the lockout. Republican Geoff Diehl, the party's nominee to take on U.S. Sen. Elizabeth Warren in November, offered a similar sentiment in support of the union last week.

"It is time for the company to listen to their workers so we don’t have any more preventable disasters like in Lawrence, Andover and North Andover," Diehl wrote.