RAIL union RMT cautioned that a prolonged spell of industrial action may be on the cards as leaders announced fresh strikes over pay yesterday.

More than 300 London Overground workers will go on strike for 48 hours on February 19 and again on March 4.

Security, station, revenue and control staff are set to walk out after Arriva Rail London offered a below-inflation pay deal.

RMT general secretary Mick Lynch warned: “If this dispute cannot be resolved then RMT is more than prepared for a sustained period of industrial action to get London Overground workers the pay rise they deserve.”

Train drivers’ union Aslef also began a series of strikes across the country yesterday that will continue today, Friday, Saturday and Monday.

Aslef general secretary Mick Whelan said that some drivers have not had a pay rise in half a decade.

The strikes were expected to be the first test of the draconian minimum service levels Bill, which could force workers to provide 40 per cent capacity, potentially making them break their own strikes.

Only state-run LNER had threatened to use the legislation — but backed down after Aslef hit the operator with extra strike days, since withdrawn.

A No10 spokesman urged operators to “be as ready to use all powers available to them to reduce the impact of rail strikes on passengers.”

Confirming the Conservative chaos on the issue, Tory backbencher Caroline Noakes complained that “the stark reality is that the legislation clearly isn’t working.

“I don’t know whether that means going back to the drawing board, whether it means amendments, but it does seem to be farcical that we were expecting this to work. It hasn’t.”