The biggest rail workers' union has rejected a proposed five-year pay deal by London Underground and launched a campaign for a "substantial" 12-month agreement.
The Rail Maritime and Transport union said it wanted an above-inflation rise over the next year to reflect the "additional workload" placed on staff as a result of the "repeated" breakdown in Tube services, a large increase in passenger numbers and the knock-on effect from a programme of staff reductions.
London Underground has made an offer of a 4% pay rise this year, followed by a rise of inflation plus 0.25% in subsequent years, covering next year's Olympic Games, describing it as "fair and affordable".
RMT general secretary Bob Crow said: "When you peel away all the spin from Transport for London, the reality is that with February's RPI inflation being 5.5%, it means that the first year of this offer is not a rise at all, but is actually a real-terms pay cut of 1.5%.
"The package falls well short of RMT's claim for a substantial, above-inflation pay rise in a one-year deal.
"This offer takes no account at all of the fact that LU is carrying record numbers of passengers, charging inflation-busting fares, cutting staff and thus increasing productivity by the back door.
"We also note the fact that LU is continuing to pay large numbers of senior managers excessive fat cat salaries.
"Add in the pressure on staff of the repeated failures in service as the infrastructure collapses and anyone can see why this derisory offer has been rejected and why this trade union will continue to press the company for significant improvements in the offer for the current year."
Howard Collins, LU's chief operating officer, said: "We've made what we believe is a very fair and affordable multi-year pay offer to the trade unions, which will see staff gain real-terms pay increases and stability over the coming years."