Restrictions on hand luggage for air passengers may have to stay in place because the threat from liquid explosives remains, say officials.
Security levels are expected to remain high
The Department for Transport said security equipment at many UK airports could not detect all liquid explosives.
But a source has told the BBC the government hopes to increase the size of allowed hand luggage within weeks.
Last week Ryanair threatened to sue the government unless it eased the hand-luggage restrictions.
On Thursday, Department for Transport security officials said they were trying to find ways of reducing the restrictions.
Hand luggage is currently limited to a small lap-top-sized bag.
The dimensions must not exceed 45cm x 35cm x 16cm (17.7in x 13.7in x 6.2in approx), including wheels, handles and side pockets.
The threat from explosives being carried in hand luggage has led to heightened security.
The officials warned the tighter rules on carrying liquids on board would continue "on an enduring basis."
The security clampdown might be relaxed if the threat level reduces, the officials said, and ministers are seeking an agreement with European partners on levels of security that are needed.
But the security experts are also trying to find technology that might help baggage screeners to spot liquid bombs in hand baggage.
There are a wide range of liquid explosives available and equipment at some airports could not detect all of them, said the officials, who were speaking to reporters anonymously.
Scientists were trying to come up with new methods, but there was a big step from a concept that worked in a laboratory to one which could be introduced in a busy airport.
Certain liquids could be used as part of an explosive device and that some of these were very difficult to distinguish from ordinary, drinkable liquids.
Also, it was far easier to detect possibly dangerous items in the type of smaller bag now being allowed to be carried on to aircraft by passengers than larger ones.
Officials showed reporters X-ray pictures of items in a large bag and items in a smaller one.
In the current enhanced security regime, the larger bag, which contained difficult-to-see hand cream, aftershave and shower gel, would have had to be rejected and a time-consuming hand search would have had to be conducted.
The officials said the aim of the current security regime was to meet the threat but to minimise the inconvenience.
They said they were happy with security arrangements which allow liquid items to be bought in airside airport shops after the passenger has passed through security.
The officials also said they were happy with the security arrangements for airside passholders and added that background checks on airport staff were the same as those in place before the current security regime was introduced.
The threat of liquid explosives would remain, as it was not possible to "uninvent" a threat, but the ways in which it was dealt with could change, officials said.