Action will affect terminals 2,3,4 and 5 from 31 August to 3 September and will be followed by a work to rule and overtime ban until 22 September.

The dispute is over new rosters which the Public and Commercial Services Union said were imposed in April. The 650 PCS members work in passport control and have already taken seven days of strike action in April, May and June.

Action will hit just as families are returning to the UK before the new school term begins.

PCS general secretary Fran Heathcote said: “We know our strike action is likely to cause serious disruption to travellers using Heathrow at the end of the summer, but the strike can be avoided if the employer listens to the concerns of our members.”

The union said around 160 staff have left since new rosters were introduced “because of the lack of flexibility and changes to the shifts”.

The PCS Union added: “Women and those with caring responsibilities have been particularly affected by these changes, and the new roster has seen long-standing and loyal staff forced out of employment in order to manage childcare and family commitments. 

“New staff have been refused flexible working applications despite changes to the law allowing employees to make a statutory request for permanent changes to their contract from day one.”

Heathcote added: “They’re being told by managers to choose between caring responsibilities and their job, which is no choice at all. The only reason they’re being forced to choose is because their managers are forcing them.”

TTG has approached Heathrow for comment.