London Mayor Boris Johnson said two-hour immigration queues at Heathrow Airport were giving a "terrible impression" of Britain as the furore escalated yesterday, just weeks before the Olympics.
The British government was forced into making an emergency statement in parliament late yesterday on passport checks at the world's busiest international passenger airport, which will be the main gateway for the 2012 London Games.
Delays of up to two hours for passengers from outside Europe were reported last week.
Frustrated passengers resorted to slow hand-clapping and jeering, while one fed-up traveller marched through the gates without showing his passport, according to reports.
Johnson wrote to Home Secretary Theresa May to voice his "serious concern" about the difficulties, which have triggered a clash between Border Force officials and BAA, Heathrow's owner and operator.
The mayor, who hopes to be re-elected on Thursday, said the delays gave "a terrible impression of the UK" and it was unfortunate that Britain's main port of entry was "gaining such a poor reputation".
"It is quite clear that because of problems at the UK border, London and the UK's reputation as a welcoming city in which to do business or travel are at stake."
In tough economic times, "it is vital that those coming here to do business find arrival an easy and welcoming process. Anything that interferes with that damages our city," added the mayor, who is standing for re-election on Thursday.
Passengers waited for up to an hour at the airport on Friday to go through border control, while there were two-hour queues on Thursday for passport holders from outside the 30-country European Economic Area.
In response to the delays, extra border staff were flown into Heathrow from Manchester in northwest England to help keep queues down on Monday, a union official told The Times newspaper.
London's Telegraph, citing emails seen by the broadsheet, also reported that the Border Force had urged BAA not to distribute "inflammatory" leaflets at Heathrow.
The leaflets told passengers they deserved better and asked them to direct their complaints to the Home Office, or interior ministry.
The wording apologised for the wait and said the airport was trying to make things "as bearable as possible".
"Both Heathrow Airport and your airline believe you deserve a warmer welcome to the UK, without compromising security," it read.
Marc Owen, the director of UK Border Agency operations at Heathrow, said the leaflet was "not all right with us" and threatened to take it up with the government.
"It is both inflammatory and likely to increase tensions in arrivals halls especially in the current atmosphere," he said in an email to BAA, according to the Telegraph.
"Please refrain from handing out or I will escalate with ministers who are likely to take a very dim view."
He also urged BAA to stop passengers photographing the queues, after images and footage appeared in British media.
Prime Minister David Cameron's spokesman said "severe weather conditions" and "late planes" were partly to blame for the delays last week, when Britain was lashed with heavy rain.
Asked whether sufficient manpower was in place at Heathrow, he said: "It is not purely about staff numbers.
"It is about how you deploy your resources effectively and better management of those resources, better prioritisation of those resources."
He added: "Our objective is to keep disruption to a minimum while at the same time making sure border security is not jeopardised in any way."
Heathrow is the official host airport for the 2012 Olympics, with around 80 percent of all visitors to the Games expected to pass through its five terminals.
The airport is building a special Olympics terminal for athletes and officials leaving after the Games and expects to have its busiest ever day on August 13, the day after the closing ceremony.
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