LONDON — Police, on high alert for a possible attack on Britain's airports, said Friday that most of those arrested in a major security operation were no longer terrorism suspects.
Police have arrested nine men under the country's anti-terrorism legislation in the last few days, as security forces take no risks with anyone seen acting suspiciously near airports. But as of Friday, six had been released, police said.
The arrests came as Britain, like the United States, is on heightened alert because of intelligence agency fears that some kind of terrorist attack might be imminent.
Britain's busiest airport, London's Heathrow, has been ringed by police and troops for the last four days amid intelligence-led fears that Al Qaeda militants might target the capital. Britain has been President Bush's closest ally in his war on terrorism.
Police temporarily evacuated part of one of the airport's terminals Friday after what a police source said was the discovery of a suspicious package.
Police also combed areas under Heathrow's flight path to prevent rocket attacks on airliners. Six men arrested in West London along the flight path were released without charge Friday, but five of them were in the hands of immigration officials.
Police said two men held Thursday near the perimeter fence of Leeds Bradford International Airport in northern England were still being questioned, but a law enforcement source said their arrests did not appear significant.
Only one arrest, that of a Venezuelan man detained Thursday after a grenade allegedly was found in his luggage at Gatwick Airport, outside London, was thought to be potentially significant. He was still being questioned Friday.