London Underground workers have given a fresh mandate for strike action while pay talks continue.

Members of the Rail, Maritime and Transport union (RMT) voted by more than 9-1 in favour of taking action if necessary over the next six months.

No strike dates have been announced but the union said it is keen to secure an improved offer on pay.

The RMT said because of changes to pay bands, not all members would be entitled to the same percentage increase which was “wholly unacceptable”.

General secretary Mick Lynch said: “Our members on London Underground are sending a clear message to management that they will not put up with substandard pay offers or any attempt to treat members unequally in any pay deal.

“We are always willing to find solutions to industrial relations issues, but our members will not tolerate an imposition of any pay deal where members are not being treated equally or fairly.”

A Transport for London spokesperson said: “We are disappointed that the RMT has balloted London Underground employees over pay and conditions.

“We have held a number of constructive discussions with our trade unions and have presented a pay offer. We are still considering their feedback to the offer and will continue to work with the unions to ensure that we reach a fair agreement for our hardworking colleagues that is also affordable and delivers for London.

“It would be in everyone’s best interest to continue to discuss this without the threat of strike action, so we can work together to support London and the wider UK economy.”