Operators say passengers are being moved through largely on schedule as UK Border Agency brings in contingency plans.

Britain’s main airports have reported no serious delays despite a walkout by UK Border Agency staff.

Heathrow and Gatwick said passport control queues were hitting Home Office targets while Manchester said it was experiencing delays of up to an hour on US flights only.

A spokesman for BAA, Heathrow’s owner and the UK’s largest airport group, said the longest queues for non-EU passengers were 45 minutes at Terminal 3, and 25 minutes at Terminal 5, the UK’s biggest airport terminal. By late morning there were minimal queues in the airport, he said.

“There are currently no queues and the longest queue that passengers have had is 45 minutes, so we are pleased that UKBA’s contingency plans seem to be working well so far.” Heathrow expects about 70,000 passengers through border control.

Luton reports disruption has been kept to an “absolute minimum” and Stansted reported that passengers were not seeing delays.

Travellers had been warned to expect delays on arrival at UK ports and airports on Thursday as hundreds of immigration and customs officers are due to join the public sector strike.

Up to half a million air passengers flying into the UK face severed disruption because of a strike by border officials at British airports. At least seven out of 10 staff at the UK Border Agency are thought to have walked out.

Earlier the UKBA had warned that “some passengers may experience delays at the border”.

“Those passengers who can travel on an alternative day may therefore wish to do so,” it wrote in a statement.

The industrial action was expected to affect travellers arriving in the UK because they are met by UKBA staff.

However, people leaving the UK were relatively unaffected because departing passengers only face security staff, employed by airport operator BAA, who were not be taking industrial action.

BAA, which runs Heathrow, Stansted, Edinburgh, Glasgow, Aberdeen and Southampton airports, said: “We have been informed by the UK Border Agency that arriving passengers should expect delays at immigration on Thursday as a result of industrial action by immigration officers who are members of the PCS union.

Mark Serwotka, PCS general secretary, said: “We expect longer queues and for managers to waive controls they would usually undertake. There will be less presence in terms of people coming and going. There is a theoretical risk to security in terms of smuggling and security of the borders, which essentially could be weakened.”

The PCS voted earlier this month to join the strikes, with a 61.1% support for the walk-outs from a turn-out of 32.4%.

Serwotka said that UKBA attempts to draft in replacement staff to conduct passport checks would not prevent delays.

He said: “It is likely that there will be severe disruptions and delays affecting both ports and airports. Our membership in Dover and Heathrow is particularly strong.”

Around 500,000 passengers pass through UK airports every day, with around one-third of those at Heathrow.

Jonathan Sedgwick, acting chief executive of UKBA, said: “We will do everything we can to minimise disruption and inconvenience to travellers. But our priority will always be to ensure that the UK border remains secure.”

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