The end of the month marks the beginning of a strike by hundreds of border force agents at Heathrow.

The strike is scheduled to run from August 31 to September 3, after which there will be a work-to-rule period starting on September 3 and lasting until September 22, during which no overtime or light labor will be done.

The long-running conflict, which started in April, is focused on forced modifications to terms and conditions, such as the implementation of rigid rosters.

According to the union, the lack of flexibility is the reason 160 employees have quit the border force.

Part-time workers and partially retired staff are being forced to change their working hours and practices, the PCS added, while new staff members are having their flexible work applications refused.

Many strikes have been threatened in the last years but few have materialised as management acceded to demands.

"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," said the PCS general secretary Fran Heathcote.

Heathrow is not just the UK's busiest airport but the largest in Europe too.

Heathrow insists they will work closely with Border Force to support contingency measures during strike periods.

The Home Office, which runs the border force, have been contacted for comment.