Authorities stepped up airport security across Asia yesterday and banned passengers to the United States and Britain from carrying liquids after London said it foiled a plot to blow up transatlantic flights.

Flights were delayed and long queues formed at airports around the region because of the new security measures, which include frisking and intensive baggage checks.

Officials in India said quick reaction police teams, armed with light machineguns, were on guard at various airports and plainclothes policemen were mingling with passengers to check for suspicious characters. "No hand baggage will be allowed on select flights to some Western destinations," said an officer of the Central Industrial Security Force, the agency responsible for the security of Indian airports.

"In all other flights, 50 per cent of randomly selected hand baggage is being manually checked."

In Japan, liquids and gels were banned from carry-on bags for passengers taking flights on US airlines or flights bound for the United States, said a spokesman for Tokyo's Narita International Airport.

"Any liquids, including something like shampoo, are banned," he said. "Obviously, baggage checks are tougher than before and take longer and therefore we are urging passengers to check in early."

British police have arrested 24 people over a plot to smuggle bombs disguised as drinks onto aircraft. US officials said as many as 10 planes might have been targeted.

Bangkok also issued restrictions on passengers flying to the United States from carrying liquids, but stopped short of banning hand baggage.

"I would advise passengers that, unless absolutely necessary, they should not carry a lot of stuff with them. It would not be convenient for their speedy transfers," Chotisak Asapaviriya, the head of Airports of Thailand PCL, told a radio programme.

In Auckland, New Zealand, passengers to the United States and Britain were banned from carrying hand baggage.

Indonesian authorities said they had stepped up airport security, but liquids and hand baggage had not been banned.

"We haven't gone that far, to ban passengers bringing those things," said Wasfan Wahyu Widodo, an official at state airport operator PT Angkasa Pura. "We just anticipate it by X-ray and metal detector."