RMT boss Mick Lynch has called for an urgent meeting with Rishi Sunak to end the strike crisis.
Walkouts across the network are expected to continue over Christmas and into the New Year due to a long-running dispute over pay and conditions.
The RMT accused the government of preventing train operators from offering a better wage deal, which ministers denied.
In an open letter to the Prime Minister, Mr Lynch said he was ‘leading the rail mandate and torpedoing the talks’.
He wrote: ‘There is no reason why this dispute cannot be resolved in the same way RMT has resolved disputes in Scotland and Wales.
‘Where the Scottish and Welsh Governments have had responsibility for mandates, pay deals for 2022 have been agreed and none of these deals have been conditional on downsizing and the erosion of safety, security and accessibility.
‘It is already a national outrage that your government has paid the train operating companies not to settle the dispute, compensating them to the tune of £300m so they have no incentive to reach a resolution .
“I don’t understand why, on top of that, your government has now torpedoed the negotiations, but I now believe that a meeting with yourself represents the best prospect for any further progress.
“We have a duty to explore all possible options to resolve this dispute and I am ready to do my part. I hope you will agree to meet me.
A government spokesman said: ‘It is incredibly disappointing that, despite a new and improved deal offering job security and a fair pay rise, the RMT continues to hold Christmas hostage with more damaging strikes.’
“The government has played its part in facilitating a fair and decent deal and the RMT and its members should vote on this deal and end this harmful disruption.”
Several industries are on strike over the next few weeks in what has been dubbed another “winter of discontent”.
Paramedics, nurses, bus drivers, airport baggage handlers, highway workers, Border Force staff, driving examiners and Royal Mail workers all voted for industrial action.
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