A union has rejected an improved pay offer for workers on the London Underground (LU).
The Rail, Maritime and Transport (RMT) union wants more than the 4.75% rise, which is 0.25% more than LU's previous offer.
The union also wants a shorter term deal, a flat-rate pay rise for some workers and a cut in working hours.
LU said the improved offer, which would run through next year's Olympic Games was "fair and affordable".
As well as the pay rise in the first years, the deal will also give increases of 0.25% plus inflation for the next four years.
'Insult to injury'
Bob Crow, the RMT's general secretary, said: "This would leave LU staff vulnerable to real-terms pay cuts in years when Retail Price index under-estimates the real rise in living costs, as it often does and would leave us unable to claim for further increases until 2016.
"Adding insult to injury, LU has dismissed out-of hand our claim for a minimum flat-rate pay increase, which would benefit lower paid grades.
"It has also dismissed our claim for a reduction in working hours and offered little or nothing on our other claims for improved conditions."
The improved offer was put forward by LU last week.
LU's chief operating officer Howard Collins said: "We have made a very fair and affordable multi-year pay offer to all of our trade unions, increased last week to 4.75% this year and Retail Price Index plus 0.25% in four future years.
"Such an offer would enable our employees' salaries to keep pace with the cost of living and guarantees an increase in real terms over the life of the agreement.
"At the same time it is realistic given the current economic situation and the pressure on TfL's finances. Discussions continue with all our trade unions."