Queues of up to six hours at border control regularly occur at Heathrow, according to its chief operating officer.

Emma Gilthorpe told the government’s Home Affairs committee that pre-Covid, the queues for EU arrivals were supposed to be 25 minutes, and 45 minutes for non-EU arrivals.

While she said she expected the length of waiting to go up during the pandemic, Gilthorpe said the levels the airport was currently seeing were “unacceptable”.

While Gilthorpe said the measures in place for quarantine hotels were running relatively smoothly, with a small number of passengers, she said the same could not be said for the border.

She was appearing before the committee as it examined border and quarantine measures.

“We are seeing significant pressure on the border and we are seeing very long queues, and that is a worry,” the BBC reported Gilthorpe as saying.

Although she knew additional resources had been introduced, the issues were caused by “the level of complexity of the processes and the way resource is being deployed”.

International arrivals must now provide proof of a negative Covid test taken 72 hours before departure to England and a passenger locator form which contains details of either a purchased hotel quarantine stay, or two test kits for at home quarantine.

Gilthorpe told the committee: “It is deeply frustrating as the operator of the airport when you have a queue full of people and you only have two desks open.

“It is rare to see all the desks manned and we have to find our way to how we make that happen so we can get that flow.”

Heathrow’s self-service e-gates at passport control are currently closed.

Gilthorpe said she hoped that by the summer, the gates would also be able to scan passenger locator forms and pre-departure testing results, but that had not yet been integrated into the system.

She also warned that if the long queues continued after international travel is permitted, it could risk the country’s economic resurgence.

“Heathrow is Britain’s hub airport, it is the front door. We have to get our economy moving and we have to make sure we are capable of receiving people,” she said.

“If you have a poor experience at the border, there’s a risk you won’t come back again. That traffic will go to Charles De Gaulle [airport in Paris], it will go to Frankfurt and we will miss out on that economic resurgence.”

Nick Jariwalla, director of Border Force at Heathrow, told the BBC: “We are in a global health pandemic – it is illegal to go on holiday and people should only be travelling for very limited reasons.

“Unfortunately, a large number of passengers are continuing to arrive without having purchased their mandatory testing packages for the second and eighth days of quarantine in the UK.

“This causes delays as passengers may receive a fine or be subject to other enforcement action.”

Jariwalla said all arriving passengers had to purchase the testing package before leaving the airport.

“We make absolutely no apologies for this,” he added. “Every essential check stops the spread of coronavirus in the UK.

“These people should not have been allowed to travel without their testing packages and we are following up with regulators and carriers to ensure the law is enforced.”

Separately, hundreds of Heathrow passport control staff are set to take industrial action.

Meanwhile, Miguel Leitmann, chief executive of airport passenger handling technologies firm Vision-Box, said: “Covid-19 protocols have had a huge impact on how businesses everywhere operate, but airports are perhaps the most intensive places as they handle tens of thousands of passengers every day from around the world.

“While covid-19 protocols, including testing and social distancing are time consuming, we can efficiently manage large crowds and cut down waiting time by using biometric and contactless technologies.

“It is important for airports and airlines to immediately upgrade their technology infrastructure before the summer travel boom, else passenger handling times would increase dramatically and create further inefficiencies.

“Airports and border forces are already experiencing severe pressure, with passenger handling times crossing over six hours in some cases.

“Some of our clients have accelerated their move towards a biometric and contactless environment – including, but not limited to Schiphol airport in Amsterdam, Emirates, Dubai International airport, the UK’s Home Office and Air Asia.

“A recent study showed that Vision-Box’s biometric contactless technology at Dubai International airport reduced immigration time for passengers down to 10 seconds.”