Seventy thousand construction workers employed by councils could strike if talks with the government fail to resolve a row over pensions.

Construction unions UCATT, Amicus, T&G and GMB are meeting deputy prime minister John Prescott in two weeks time. The issue at stake is a plan to make temporary cuts to workers’ entitlements. These include a 1% increase in their pension contributions and a rise in the age of early retirement for non-health reasons from 50 to 55.

The proposals have been put forward by the Local Government Association after the unions fought off an earlier plan to cut benefits. The LGA argues that this defeat has created a £435m deficit in its members’ pension provision, and that it has to be met by an emergency benefit reduction or a rise in council tax.

In a letter sent to John Prescott on Monday, the unions responded that the deficit was only £250m, and could be recovered after longer-term measures were introduced.

Alan Ritchie, UCATT general secretary, said: “We reserve the right to reballot our members for strike action, but we respect the judgment of the deputy prime minister and are confident that he will make the right decision.”

We respect the judgment of the deputy prime minister and are confident that he will make the right decision

Alan Ritchie, UCATT general secretary

Any strike ballot would include construction workers directly employed by local government bodies, and those whose employment is transferred to local bodies under the Transfer of Undertakings (Protection of Employment) regulations. Craft workers constitute most of the workers in the sector.

The dispute last year centred on the government’s attempt to remove the so-called “rule of 85”, which states that workers can retire without cuts in benefits if the sum of their age and length of service totals 85 years. The original plan had been to scrap the rule in April this year, but this move was rescinded when union members voted overwhelmingly in favour of strike action.