Heathrow has become the biggest airport in the world to allow passengers to carry two litres of liquids in their bags through security - just ahead of the half-term holidays.

The airport has finally completed the rollout of new high-tech CT scanners. Electronics such as laptops can also be left in luggage, while clear plastic bags for liquids no longer have to be used. Other airports with the scanners include Gatwick, Bristol, Belfast Edinburgh and Birmingham which have increased to a two-litre limit.

At most UK airports, passengers can keep liquid containers of up to 100ml in their luggage, without having to remove them and use clear plastic bags. Other airports that have the new scanners installed are waiting for the green light from the Department for Transport (DfT) to raise the limit from 100ml.

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Heathrow said the scanners, which provide better images of cabin bags, could service “thousands of passengers an hour with significantly greater efficiency, while maintaining high safety and security standards”. The rule change only applies to flights leaving Heathrow, and passengers must check restrictions on luggage at the airports they are returning from before boarding flights to the UK.

Heathrow chief executive Thomas Woldbye said the £1bn package of upgrades would mean passengers could spend “less time preparing for security and more time enjoying their journey”. Of the world's busiest 10 airports, Heathrow is the only one to have scrapped the 100ml rule for liquid containers on international flights.

A DfT spokesperson said: “Heathrow is the latest UK airport to complete its rollout of next-generation security equipment for passengers, helping ensure security checks remain robust and can be completed smoothly.

“Airports are responsible for the installation and operation of security equipment. Passengers should continue to check security requirements with airports before they travel and come prepared with liquids in containers no larger than 100ml in hand baggage unless advised otherwise.”

The rollout of the new high-tech scanners across the UK has suffered a series of setbacks over the past few years.

Boris Johnson promised in 2019 that the rules about taking liquids through security in containers of no more than 100ml, inside plastic bags, would be scrapped by the end of 2022., but the pandemic delayed that.

In December 2022, the Conservative government promised state-of-the-art scanning equipment would be installed in security lanes by June 2024 in the “biggest shake-up of airport security rules in decades”.

Then-Transport Secretary Mark Harper said the dominance of “tiny toiletry” was nearly over. The June 2024 deadline turned out to be unachievable for the biggest airports - although a number of smaller ones, with fewer lanes, did install the scanners.