After Britain foiled a terrorist bid to blow up a number of planes flying from the United Kingdom to the United States, a number of airlines have put in stringent security measures.

British Airways has announced only essential travel items such as passports, tickets and wallets will be allowed as hand baggage. These too have to be carried in transparent plastic bags.

Essential medicines for the duration of the flight can be carried only if there is an accompanying prescription in the name of the passenger.

No liquids are allowed. It was discovered that terrorists were planning to cause mid-air explosions with the help of masked liquid explosives that would be carried into the aircraft as hand baggage.

Passengers have been told that no electrical or battery powered items -- including laptops, mobile phones, iPods and remote controls -- can be carried as hand baggage. These items will have to be checked in.

Baby milk and juices can be carried only if a child is accompanying the passenger. The liquids would be checked before being allowed on board.

These restrictions would apply to all flights passing through London [Images].

Most of the other airlines that fly from India to the US have announced enhanced security measures -- irrespective of whether they pass through London or not.

"We are following the UK system," said Prasad Rao, assistant general manager, Air India. "All hand baggage except essentials will have to be checked in. Passengers are allowed to carry a certain weight in their checked in baggage and their hand baggage. The total weight should not exceed this (weight)," he added.

Keyur Chotalia, Emirates' public relations officer in Mumbai, said, "As of now we have not taken any new steps to enhance security. Security measures that are normally followed will be strictly implemented."

KLM and NorthWest Airlines share the same infrastructure in India. Their reservation agent in Delhi, Ritu Chadda, said restrictions on hand baggage would be implemented on all their flights. No electronic items and no liquids would be allowed. Only essential items would be allowed to be carried in transparent plastic bags. Checked in baggage should not exceed 23 kg in weight. Normally they allow 10 kg more as hand baggage. Passengers would be allowed to check in this hand baggage only if there is availability of space. They cannot insist on it.

Passengers travelling to the US are also advised to visit the web site http://www.tsa.gov for further information.