Colleges across the country risk industrial action in the spring as a result of their "extremely disappointing" failure to deal with rising staff workloads, the University and College Union (UCU) has warned.
Barry Lovejoy, UCU's head of FE, wrote to all college principals in England and Wales in November, reminding them of procedures for altering working hours that had been agreed by the FE unions and the Association of Colleges (AoC).
Warning that pressures on workload could "seriously jeopardise quality and the health and well-being of staff", he asked colleges to confirm their commitment to tackling the issue.
But Mr Lovejoy told TES that fewer than 40 of around 260 colleges he wrote to had replied. Of these, fewer than 10 gave a "satisfactory" response.
He added that the union would consult with its branches to discuss whether members were prepared to ballot for industrial action, with a decision expected to be made at UCU's FE committee meeting in March.
"Unfortunately, we have had a very poor response in terms of the number of colleges replying," Mr Lovejoy said. "Most of the ones which have replied just said they were confident they were complying with their legal obligations. Quite frankly, that's extremely disappointing.
"In January, I will be writing to colleges again, informing them that they risk a trade dispute arising on the basis that it's a recognised agreement. In particular we are asking them to comply with a risk assessment on staff working hours.
"We will be talking to our branches to see if they wish to declare a trade dispute with their colleges, and whether they wish to be balloted for industrial action on this issue."
The industrial campaign would initially be likely to take the form of action short of a full strike.
A recent survey of UCU members working in FE colleges revealed that stress levels have increased since 2008. In 14 colleges, more than a third of members surveyed said they worked 50-plus hours a week.
But while UCU may be gearing up for action on working conditions, general secretary Sally Hunt told TES that she currently had no plans to "jump" into a national strike with the other teaching unions over pay or pensions.
Despite the fact that UCU's FE members voted to reject the Association of Colleges' pay deal for 2012-13 - a 0.7 per cent rise for staff earning #163;15,000 or more - Ms Hunt said they had signalled that they were not currently prepared to lose pay as a result of striking.
"We don't want to take action this year on pay," she said. "That's not because we're saying it's all fine. What people are saying is: 'There are choices we are making and we want you as the union to respect that.'
"I am clear that the pay is crap at the moment and has to be dealt with, but we've got to pick the moment when we deal with that."
Ms Hunt added that UCU had held talks with the other teaching unions about workloads and concerns over Ofsted. "There are areas where we are talking with our sister unions; we don't want to hide that. If we are working together, good. Does that mean we will jump because other unions are doing so? No, it doesn't. Our responsibility is to our members and we will consult right the way along the line before we make any decisions on that."
Emma Mason, the AoC's director of employment policy and services, said its members took their responsibilities for the welfare of their staff seriously. "Any decisions not to formally adopt the national joint agreement should not be taken as an indication that this is not the case," she added.
Ms Mason said that the agreements with UCU over workload were "recommendations only", adding: "It is for each college to determine whether or not the working hours joint agreement is relevant to their organisation ... It is disappointing that UCU intends to call a national dispute regarding an issue that is for local discussion based on evidence of a local issue."