A transport union is set to ballot rail staff across the UK in what could lead to “potentially the biggest rail strike in modern history”.

The Rail, Maritime and Transport Workers (RMT) union is balloting 40,000 members on the move, which network sources have reportedly said would create “serious challenges” in keeping goods moving and supermarket shelves stocked.

The union's general secretary Mick Lynch said if it were to go ahead a national rail strike would "bring the country to a standstill" but said the safety of staff and passengers was their priority. 

RMT is balloting members amid concerns over pay, compulsory redundancies and safety concerns across a number of rail operators.

The vote, which is due to close on Tuesday, includes staff on Network Rail and 15 train operating companies. 

The union has also announced it intends to ballot members in Scotland for strike action, following what it describes as a “derisory” 2.2% pay offer by ScotRail and proposed timetable changes which it branded a “kick in the teeth” to workers.

ScotRail has cut 700 services, starting on Monday, amid a shortage of newly trained drivers due to the pandemic. 

The lack of newly-trained drivers has seen many drivers forced to work overtime and on their rest days. 

Drivers' union ASLEF said it would ballot its members or industrial action over pay. A number of drivers have since refused to work overtime or on rest days.

Specific details about the potential UK-wide action have not yet been outlined by the RMT.

Transport Secretary Grant Shapps will meet with the Prime Minister and Chancellor next week to discuss the threat amid fears in Whitehall that the action could be worse than the junior doctor walkout in 2015, The Times has reported.

A senior rail source is quoted by the paper as saying: “We want to keep people and goods moving but there is no doubt we face serious challenges.

“There is an awful lot of work going on behind the scenes including around what the timetable might look like. One option is times of the day when only freight services operate.”

The Rail Delivery Group (RDG) has urged against what it describes as a “premature” ballot but said it was drawing up contingency plans to try and lessen the effects of any potential strike.

RMT general secretary Mick Lynch said: “Railway workers have had to contend with pay freezes, the prospect of losing their jobs and repeated attacks on their terms and conditions.

“Removing 2,500 safety-critical jobs from Network Rail will spell disaster for the public, make accidents more likely and will increase the possibility of trains flying off the tracks.

“Train operating companies have praised our members for being key workers during the pandemic but have refused to keep staff pay in line with inflation and soaring living costs.

“As a result, thousands of railway workers have seen their living standards plummet and have run out of patience.

“The way for trade unions to effectively take on the cost-of-living crisis is to stand up for their members at work and take industrial action when employers are not moved by the force of reasoned argument.

“A national rail strike will bring the country to a standstill, but our members’ livelihoods and passenger safety are our priorities.”

He added: “We believe in modernising the railways but we do not believe in sacrificing thousands of jobs, constant pay freezes or making the railways unsafe.

“That is what government plans will mean for the railways if RMT and other transport unions don’t mount a comprehensive defence of the industry.”

The ballot will be among RMT members on Network Rail and Chiltern Railways, Cross Country Trains, Greater Anglia, LNER, East Midlands Railway, c2c, Great Western Railway, Northern Trains, South Eastern Railway, South Western Railway, Island Line, GTR (including Gatwick Express), Transpennine Express, Avanti West Coast, and West Midlands Trains. It closes on Tuesday and the results will be known the following day at 10am.

Tim Shoveller, Network Rail’s regional director, said: “We are disappointed that the RMT has taken this decision and urge them again to work with us, not against us, as we build an affordable railway fit for the future.”

Mr Shoveller added: “We would not consider any changes that would make the railway less safe.”

A spokesperson for the Department for Transport said: “With passenger numbers down and our railways on life support, we need to act to make them fit for the future.

“We want a fair deal for staff, passengers and taxpayers so money isn’t taken away from other essential public services like the NHS.

“The unions should talk to us about the proposals before causing irreparable damage to our railways, and strikes should be the last resort, not the first.”