The country's largest trade union, Unite, has rejected the government’s revised offer on pensions for NHS workers, signalling more trouble ahead on the issue following the national strike in November.

Unite said that the proposed reforms are a “pernicious attempt” to make staff pay more, work longer and get less when they retire.

Before Christmas, Treasury Minister Danny Alexander announced that the majority of unions (26 out of 28) had agreed to the new terms in principle, which include a rise in contributions and the pension age.

Unite, which represents 100,000 NHS workers, was one of the two unions that did not agree to the revised deal in December. Instead it chose to reserve its final judgement, while the Public and Commercial Services union rejected the changes outright.

Now less than three weeks later, Unite’s health sector national industrial committee (HSNIC) has also rejected the pension proposals as unfair.

The union said contributions for a high proportion of staff under the proposed deal would increase from 6.5 per cent to 9.3 per cent by 2014/15, while the rise in pension age could mean paramedics and nurses doing work requiring heavy lifting into their late 60s.

Unite also said that the proposed accrual rate for NHS staff was “worse than the planned rates for other public sector schemes”.

This is because accrual will be based on career average earnings, affecting women who take career breaks to have children, it said.

Len McCluskey, the union’s general secretary, said: “Our NHS executive unanimously rejects the government’s pernicious attempts to make hard working and dedicated NHS staff pay more, work longer and get less when they retire.

“The government’s attacks on public sector pensions are politically motivated, as part of an overall design to privatise the NHS, cut public services, break-up the national pay agreements, and disrupt legitimate trade union activities and organisation.”

A Department of Health spokesman called Unite’s decision “disappointing” and said the new NHS pension scheme was “a good deal”.

"The government has made clear this is our final position on the main elements of scheme design, which all the health unions, except Unite, agreed in December to take to their members,” said the spokesman.

“Unite represents approximately 7 per cent of the NHS workforce - it is important to remember that it is the decision of the unions representing the majority of staff which will determine the final NHS pension deal. Further discussions are being held to work on the remaining details."

Unite called on the government to return to meaningful negotiations, while the HSNIC is set to meet on 11 January to discuss future strategy.