Scotland's largest teaching union, the EIS, has ratcheted up the pressure on the Scottish government over pensions by announcing plans to hold a consultative ballot over further industrial action, should the current negotiations fail to find a "Scottish solution".
Last year, Scottish teachers took their first strike action in a quarter of a century in protest at Westminster government pension reforms.
The Scottish Secondary Teachers' Association suspended its work to contract last year as a sign of good faith in the discussions being held with the Scottish government. But acting general secretary Alan McKenzie warned that the union's action would be reinstated - or a strike ballot held - if the talks break down.
Larry Flanagan, EIS general secretary, said there was "a degree of anger" about the way the Scottish government had handled the recent consultation on contribution increases.
The union side had been arguing for younger teachers to be given greater protection from contribution increases, but the Scottish government had chosen instead to adopt the English model, said Mr Flanagan.
"We have a sense of negotiating at arm's length with the UK Treasury when we should be negotiating with the Scottish government," he added.
Mr Flanagan said the combination of these issues and a "not very positive negotiating meeting" had pushed the unions towards a recognition that the negotiations may prove fruitless, in which case it would need to be ready to respond.
A government spokesman said it remained committed to the discussions process with teachers' and employers' representatives. "The Scottish government is opposed to the increases to public sector employees' pension contributions. We are required by the UK government to implement them in order to avoid a reduction to the Scottish budget equivalent to the amount they are expected to raise," he said.