STRIKE action will mean that London Overground’s Windrush line cannot operate safely tomorrow, the RMT union has warned.

Signalling, telecoms and track maintenance workers will walk out after contractor Clershar CS refused to improve its offer of a below-inflation 1.5 per cent pay rise.

The union warned that the employer was “recklessly” incentivising overtime across the safety-critical workforce instead of addressing the pay aspirations of members and dealing with understaffing.

This is creating “unacceptable risks” for passengers, RMT added.

Twenty-four-hour strikes will take place today on March 26 and April 23.

RMT general secretary Eddie Dempsey said: “Cleshar has failed to table a new offer and has left our members with no option but to take strike action.

“Instead of addressing low basic pay, the company is driving excessive overtime to keep the job covered.

“The employer is displaying a cavalier attitude which is totally unacceptable.”

Cleshar was contacted for comment.