Motor giant Ford was warned today it faced legal action over the pension rights of thousands of workers who transferred to a car parts firm which then went into administration.
Unite accused Ford of providing "misleading" advice to the employees, who switched to Visteon in 2000, telling them that their accrued pension rights would be protected.
Up to 4,000 workers were told they could lose as much as half of their pension entitlements when Visteon went into administration last year.
The former factory workers, who used to be based in Belfast, Basildon in Essex, and Enfield in north London, have been campaigning for the past year to force Ford to take back responsibility for their pensions, and occupied some of the plants after Visteon went into administration.
Workers at the Dunmurry factory held sit-in protests in April last year after they were sacked, and Ford showrooms were picketed across Northern Ireland.
Unite's national officer, Roger Maddison, said: "Hundreds of workers, many of them close to retirement, were sacked at a minute's notice and lost their pensions. We believe Ford misled many of these workers, leading them to believe their pensions were safe with Visteon."
Unite has written to Ford saying it will press ahead with legal action if the dispute is not resolved.
Ford said it met or exceeded its obligations when Visteon became fully independent, covering the transfer of employees to Visteon UK, and their pensions into the Visteon fund.
"The situation for former Visteon UK employees is unfortunate, but the responsibility for administering and funding their terms and conditions was Visteon's, including managing its pension fund," Ford said in a statement.
"Ford's obligations to its former employees were fully discharged and Ford believes there is no basis for resuming liability for benefits transferred to Visteon.
"Ford has stated that it will not provide further assistance to affected parties. This position was confirmed at a meeting on January 22 between senior Ford executives, representatives of the Unite union, and ex-Visteon employees."