Heathrow and Gatwick airports are preparing for a repeat of the chaotic scenes in August when they introduce emergency measures to cope with the Christmas exodus, which begins in earnest tomorrow.

More than half a million people are due to pass through Heathrow between Friday and Sunday. Next week Thursday, Friday and Saturday will also be extremely busy, with the peak on Friday, when 194,000 people will pass through the airport, 30,000 more than on a normal day.

BAA, which owns Heathrow, Gatwick and Stansted, fears that its security screening system will be unable to cope with the extra numbers and has put up marquees at Heathrow’s Terminal 4 to cope with the overflow. At Gatwick, BAA has told airlines to expect 100-minute delays for passengers going through security.

This Christmas will be the first test of whether BAA has put in place sufficient measures to prevent long delays in busy periods. The authority promised to recruit more than 250 extra security staff at Heathrow, but only 100 of these will be trained in time.

The system was already struggling at Heathrow yesterday, with queues for check-in and security much longer than normal at Terminal 4. Virgin Atlantic said that there were very long queues at Gatwick.

Thousands of flights were cancelled in August, when the Government introduced much tighter security rules after the discovery of an alleged plot to blow up transatlantic airliners. The worst chaos was at Heathrow, where passengers were herded into hastily erected marquees and left waiting for hours without food or drink.

The security measures were partially relaxed on November 6, but passengers are still allowed only one piece of hand luggage. They can take liquids, including creams, pastes and sprays, through security in a clear plastic bag, as long as each bottle or container has a capacity not exceeding 100ml.

Last month BAA said it was recruiting 500 new security staff across all its seven airports to reduce delays at security checkpoints. But it emerged yesterday that the full complement will not be reached until the end of January.

BAA said recruits had to go through background checks covering the previous five years and then be trained for six weeks, with the whole process from placing advertisements to recruits starting work at check- points taking three months.

A spokesman for Virgin Atlantic said that passengers at Gatwick yesterday had been forced to queue back to the railway station. “BAA has got to put more resources in,” he said. “They have had plenty of notice and can no longer use the excuse that they suddenly have to cope with extra security measures. They must open all the security channels, some of which are currently closed.”

He added that security checks were taking longer than normal because people were wearing heavy winter coats, which had to be screened separately.

BAA has appealed to the Civil Aviation Authority against penalties of £1.7 million, which it has been told to pay to airlines to compensate them for the delays in August.

BAA claims that the problems were outside its control and that it could not have acted more quickly to reduce the queues.

A spokesman for the airports authority said: “The marquees have been erected purely as a contingency plan for the busy Christmas period. It makes sense to have them there in case of the worst-case scenario.”

Times recommends

• Bogus websites are conning hundreds out of their holidays
• The complete last minute holiday guide
• Croatia: the flashing blades of Korcula