SECURITY restrictions on hand luggage will be partially lifted before the end of next month, with passengers likely to be allowed to take bigger bags on board aircraft, The Times has learnt.

The ban on liquids will remain, however, because the X-ray machines being used cannot distinguish between harmless fluids and those that could be used to make bombs.

The Government is under great pressure from airlines to restore the internationally recognised limits on the size of hand luggage. Last week, the Department for Transport (DfT) imposed a smaller size equivalent to a large briefcase.

An official told The Times: “We are keen to allow normal-size hand luggage as soon as possible and it should be possible before the end of September. It is going to be weeks, not months.” He said that the change was likely to be justified on the grounds either that the threat had reduced or that security staff were better able to cope with larger bags. He added that staff were becoming more experienced at spotting liquids on X-ray images.

Restoring the previous limits on hand luggage may also be necessary to persuade other countries to adopt common rules, such as a global ban on the taking of liquids through airport security.

Airlines are losing thousands of business passengers, who are unwilling to fly because they cannot carry on board their midsize suitcases with wheels.

Some budget airlines, including Ryanair, have also been trying to maximise profits by getting passengers to carry their own luggage rather than checking it into the aircraft’s hold. Ryanair said yesterday that it was planning to proceed with legal action against the Government to recover the £2 million that it has lost so far from the security-related delays and cancellations.

Officials at the DfT security and contingencies division explained yesterday why the present security measures were introduced. They denied that the decision to hold an unprecedented media briefing had been influenced by Ryanair’s threat to begin legal action today.

The officials said that they were studying various new screening systems that can detect potentially explosive liquid. But they said that it was not possible to “uninvent” the recently recognised threat from liquids. Liquid in hold baggage did not present a problem because the larger scanners used to screen it were more sophisticated and better able to detect suspicious substances.

The screening of hold baggage is also simpler because staff are looking for complete explosive devices with detonators and timers. Staff checking passengers and hand luggage have to allow for the possibility that items for a bomb could be taken separately through security and assembled on board.

The officials said that the easing of restrictions did not depend on the introduction of better scanners, which will take many months to test.

One senior official said: “There is an issue which will be continuing about liquid explosives in hand baggage. But I don’t want to give the impression that the [security] measures are necessarily enduring.

“We are trying to find ways of handling that work which get balance between convenience to passengers and supporting the development of a competitive industry.”

He rejected demands from some airlines for the DfT to pay for extra airport security.

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