Mr Lynch met with the new Transport Secretary Mark Harper on Thursday morning.

He said the minister agreed to put in writing the ways the Government believes the RMT's dispute with rail operators can take “steps towards a resolution”.

Mr Harper also told the RMT he will “consider” setting up a liaison group at ministerial level so the rail industry and trade unions can speak with them about how a settlement can be agreed.

But the upcoming strikes will not be called off until union members have assurances over pay, working conditions and jobs, Mr Lynch said.

Staff across Network Rail and 14 train operating companies are due to walk out on December 13, 14, 16 and 17. Further strikes are planned on January 3, 4, 6 and 7.

There will also be an overtime ban across the railways from 18 December until 2 January, meaning staff will not work on rest days over the Christmas period.

This is likely to reduce services on non-strike days as well, badly affecting those travelling over the festive period.

Speaking outside the Department of Transport offices in Westminster, Mr Lynch said: “If we call off the strikes we will never get a settlement.

“We have not called a strike for seven weeks and nothing has happened.

“Anyone that’s been involved in industrial relations knows that there’s got to be leverage and pressure at the table from both sides.”

He added: "We called the strikes off two weeks ago, we gave a two-week period - where we were told we would get a tangible outcome, we would get commitments and proposals. We've got none of that.

"So, once bitten, twice shy, in that sense."

However he added that the meeting with Mr Harper, who has been in the job a month, was “positive” because they had “got rid of the bellicose monsters that we used to have”.

“We’re now starting to get a dialogue,” Mr Lynch said.

“We’ve said to him that there’s no good having these warm words.

"We’ve heard them from his predecessor, Anne-Marie Trevelyan, but nothing actually happened. So we want him to set down in writing what he’s going to do about the mechanics of how a resolution will be facilitated.”

Mr Lynch added that believes the Department for Transport is being constrained by the Treasury in the rail dispute.

"We think their problem is that the Treasury is pulling their chain, and they're not independent actors," he said.

"Now they've got to assert themselves as an independent department and get to grips with the crisis that's been created in our industry."

In a statement, Transport Secretary Mark Harper said: "This morning I had a constructive meeting with Mick Lynch, where we had an open and honest conversation about the serious challenges facing the railways.

"We have common ground - we both want the dispute to end and we both want a thriving railway which delivers for passengers and workers alike. To achieve this, though, we need to work together, across the entire industry, to ensure our railway industry thrives.

"There is a deal to be done and I believe we will get there - I want to facilitate the RMT and the employers to reach an agreement, and end the dispute for the benefit of the travelling public."