There was more bad news for passengers facing long queues at Heathrow last night as it emerged that immigration staff at the airport – and across the country and abroad – are to stage a one-day strike in a dispute over public sector pensions.

The Immigration Service Union (ISU), which represents 4,500 Border Agency staff, said its members would walk out next Thursday, 10 May.

The union said it was in dispute with the Government over plans to increase the retirement age for public servants, linking it to the state retirement age.

The strike is likely to cause severe disruption at airports, including Heathrow, which is already being hit by massive delays. The Government has pledged to draft in 80 extra immigration staff after criticism about long queues at Heathrow.

The ISU said it believed managers would be used to cover for its members during next week's strike. "The Government will run some kind of skeleton service. If the airlines advise people not to travel on that day things might be quiet," said a union spokesman. "We want a fixed retirement age of 65 for immigration staff."

Immigration minister Damian Green admitted the Border Force needed to change the way it operated, and said the extra staff would start work this month.

But Mark Serwotka, general secretary of the Public and Commercial Services union, warned: "Drafting in staff from other areas of an already overstretched agency is like putting a sticking plaster on a serious injury, it will do nothing to stop the inevitable from happening."