Authorities in Britain, France, Germany, Italy, Spain and the Netherlands either increased passenger checks or reinforced security measures already stepped up ahead of the busy Christmas and New Year travel period, officials said.
The measures follow a formal request from the U.S. Department of Transportation to airports worldwide to ratchet up security following the failed Christmas Day attack on a Delta Air Lines flight by a Nigerian suspect, officials said.
German authorities said they were considering increasing airport security but hadn't done so yet.
British airports group BAA, which manages two of the 10 busiest airports in Europe -- Heathrow and Gatwick -- said airlines had strengthened security and travellers should expect delays during one of the busiest travel periods of the year.
Passengers travelling to the United States should expect their airline to carry out additional security checks prior to boarding, the company said in a statement.
A spokesman for Aeroports de Paris said the U.S. transport authority had specifically asked airports to search passenger luggage more thoroughly and to carry out extra pat-down searches of passengers before they board U.S.-bound flights.
We received instructions from the U.S. Federal Transit Administration last night and it's up to the individual airlines to put them in place, the spokesman said, referring to a unit of the U.S. Department of Transportation.
The instructions were sent to all the countries in the world and apply to all airlines travelling to the U.S.The vice-president of the European Commission, Jacques Barrot, said European authorities were in touch with the United States and would do everything to keep airline security tight.
This incident shows once again that vigilance is necessary at all times in the fight against terror, he said.
AIRPORTS ON ALERT
In Rome, home to Europe's sixth busiest airport, civil aviation authority ENAC confirmed it had ordered security for all flights bound for the United States to be beefed up.
In Madrid, passengers were being held in a sterile zone, similar to measures taken after September 11, and were being told to check in as much luggage as possible to reduce carry-on baggage, an official with a U.S. airline said.
The Dutch national counter-terrorism agency NCTb said procedures at Schiphol Airport in Amsterdam, used by the attacker as a transit point from Nigeria, had been heightened in line with the U.S. request.
A spokeswoman said the measures would be implemented for an indefinite period, but declined to elaborate.
Germany's interior ministry said it would keep security measures under review. As always we assume a very high danger for Germany, but the incident in America has not changed the security situation, a spokeswoman said.
We are reviewing at the moment whether we will selectively raise our standards. We are in close contact with the Dutch security authorities.British Airways, which operates dozens of flights to the United States daily, said passengers would be subject to baggage restrictions in order to process tighter security.
For all customers departing on a flight from Heathrow or Gatwick to the U.S. only one item of hand luggage is allowed, the airline said. Customers travelling to other destinations outside the United States are not affected.
A 23-year-old Nigerian, named by U.S. media as Abdul Farouk Abdulmutallab, was in custody on Saturday after attempting to set off the explosive device shortly before landing in Detroit.
He was overwhelmed by passengers and crew as he tried to ignite the device, and suffered severe burns in the process. At least two passengers received minor injuries, authorities said.
Dutch counter-terrorism authorities said they were trying to figure out where the suspect had come from, how he had been screened and how he had managed to board the flight.
British authorities are investigating reports the man had been a student in Britain, a counter-terrorism source said.
(Additional reporting by Rosalba O'Brien and Bill Maclean in London, Sophie Taylor in Paris, Ben Berkowitz and Aaron Gray-Block in Amsterdam, Phil Pullella in Rome, Itziar Paneda and Tracy Rucinski in Madrid and Brian Rohan in Berlin; editing by Myra MacDonald)