There were renewed warnings of a summer of travel chaos at British airports yesterday as the Government insisted it would not slow the introduction of passport scanning.
The equipment - designed to read high-tech biometric passports - has already caused long delays at Stansted.
Lin Homer, the chief executive of the Border and Immigration Agency, yesterday said the devices would be installed at all major ports by the end of the year.
The decision has infuriated several airlines, who already face passenger complaints over the security restrictions on outbound passengers' cabin luggage, and fear that extra security checks will mean long delays for incoming passengers.
But Miss Homer played down the threat and insisted that passengers would face only a "slightly longer wait''.
"We have to look at individuals and I make no apology for that,'' she said.
The worst difficulties have been encountered at Stansted, where some passengers have had to wait for over an hour. Last week, Michael O'Leary, the chief executive of Ryanair, criticised the delays.
Within the industry, the greatest fears are the impact the new machinery will have at Heathrow which, according to one industry source, was already on a knife edge.
The crunch time will be early morning when long-haul flights arrive from Asia and North America.
A spokesman for the Airport Operators Association said: "We have met the Government and have made it clear we need more front line immigration staff.''
But Miss Homer insisted that the number of officials checking inbound passengers has been increased.
The delays, she said, were due to a number of factors: "There has been some bunching of flights that has meant there have been times when we have been dealing with significantly more people than normal.''
Another concern is that the delays could have a snowball effect in the baggage halls, with bags lying uncollected on baggage carousels while their owners are still in the immigration hall.
"Once you have a backlog anywhere at Heathrow - even on the spur road coming in, it all falls over,'' an industry source said.
But Miss Homer said that technology could, in the long term, ease delays. The 90,000 people who have enrolled in an iris recognition system are already getting into the country more quickly, she said.
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