Drivers on London Underground are to be balloted for industrial action in a dispute linked to the Night Tube.

Scores of members of the Rail, Maritime and Transport union will vote in the coming weeks on whether to launch a campaign of action.

The union accused LU of failing to honour an agreement on career progression into full-time jobs for drivers on the night service, which was launched just over a year ago.

RMT general secretary Mick Cash said: “Staff are rightly angry and frustrated that an agreement that would have allowed Night Tube drivers to progress to full-time driver jobs is being flouted by the company.

“That is wholly unacceptable and has left RMT with no alternative but to declare a dispute and begin preparations for a ballot.

“RMT remains available for talks but we will not sit back while our members are denied the career opportunities they deserve.”

A planned strike by drivers in Aslef was called off earlier this month after talks over demands for a four-day week and a reduction in weekend duties, which the union said had been agreed as part of the deal to set up the Night Tube.

Nigel Holness, operations director for London Underground, said: “Successful Night Tube services have been running for over a year in line with agreements reached with the unions.

“We have already met them on this issue, acknowledged their concerns and have agreed that swift attention is needed.

“The threat of a ballot is wholly disproportionate and unnecessary.”

LU says the Night Tube has been a big success, adding £171 million to London’s night time economy‎.