Sheffield Supertram bosses have expressed their disappointment after workers announced a further eight days of strike action in a row over pay.
Around 200 drivers and conductors working on the city's tram system have already taken five days of strike action in the dispute over pay rises.
Unite has now revealed further strikes on August 18, 20, 22, 28 and 30 August, as well as on September 1, all starting at 1am. There will also be a 48-hour strike starting on August 24.
The union said the action has been taken after Supertram bosses did not respond to their calls for a meeting tomorrow.
But Supertram bosses said they have provided a 'strong pay offer' which has been rejected.
Tim Bilby, managing director of Supertram, said: "We are disappointed that further strike action is planned and that our customers may be inconvenienced again by the actions of the union.
"We have provided a strong pay offer, which is higher than the average pay settlement in the UK economy today, during a period in which we are not making profit due to the effects of rail replacement work .
"We are willing to have further discussions with the union, provided these are realistic and meaningful, and we will work hard to minimise disruption to our customers on the planned strike days."
The dispute centres on a pay rise offer that the union claims amounts to just 26p an hour extra. They rejected the three-year deal and are campaigning for a higher rise.
The union previously pointed out that train drivers earn a minimum of £35, 000 a year train conductors are on at least £20, 000. In comparison, Supertram drivers currently earn £23,035.25 a year and conductors are on £18,370.83.
Unite members voted by 91 per cent in favour of strike action and by 95 per cent for industrial action short of a strike.
Despite the latest action, Unite regional coordinating officer Steve Clark said the union is still willing to get back around the negotiating table.
He said: "Hopefully, the people of Sheffield will see which side is making every effort to resolve this dispute.
"The bosses are playing hardball and it is the commuting public that will suffer travel misery as a result.
“Our door is open 24/7 to resolve this dispute before the next round of strike action is due.”