Unless a deal is reached, the biggest rail strike in a generation will continue for a full year and beyond with further action, the leaders of the RMT union have warned after a final negotiation to avoid a failed strike action in the coming days.

Network Rail’s 40,000 RMT staff and 13 train operating companies will cause major disruptions across the rail network for six days from Tuesday.

RMT leader Mick Lynch told the FT that there was “no chance” at the moment to reach a back-to-back agreement with the government and the rail industry on low pay rises, potential redundancies and changes to working practices.

“There will be a strike movement and other unions will join us . . . I expect more strikes,” Lynch said.

After members voted to strike in May, RMT leadership has a six-month mandate to initiate a strike by the end of November. But Lynch said if a deal could not be reached, he would revisit members for a new mandate to extend the dispute into next year.

“We will extend the mandate until we resolve the issues in the dispute,” he said.

Lynch also called on the government to “unblock” the rail industry, allowing companies to negotiate freely with unions.

Ministers have effectively reined in the industry’s finances following changes during the pandemic, but Transport Minister Grant Shapps said this week it was up to the rail network and train operators to negotiate.

“If we had our normal negotiations, we might have made progress, but the administration is standing in the shadows . . . they want this dispute,” Lynch said.

Mr Lynch said the salary increase being discussed – just 2 per cent due to public sector wage caps and rail budget cuts – would not be enough given inflation is expected to hit 11 per cent this year.

Earlier this week, Shapps said the strike action was an “incredible act of self-harm” just as people were returning to railways after the pandemic.

He said the railway needed to save money after receiving £16bn of taxpayer support during the pandemic, and that RMT leaders refused to discuss modernisation.

Shapps warned the strike could cost thousands of jobs if it caused more passengers to switch to remote work.

“Don’t risk the industry and your future. Don’t risk putting yourself out of a job,” Shapps said in a speech this week.

Industrial action is scheduled for Tuesday, Thursday and Saturday, but passengers will face six days of disruption from Tuesday morning to Sunday as trains won’t be available and night shift workers won’t be on duty.

Network Rail, the public agency that runs rail infrastructure, plans to run only about 4,500 of the 20,000 normal trains per day on strike day and shut thousands of miles of track across swathes of the country.

Trains only run 11 hours a day between 7.30am and 6.30pm and passengers are urged to travel only when necessary.

RMT workers are also set to strike on the London Underground on Tuesday, in a separate dispute with Transport for London.