British officials considered closing Heathrow Airport in response to reports of a terrorist threat, a senior minister said Wednesday, but decided that would be "catastrophic" for the economy.
"The immediate threats are not verifiable, therefore we are working on finding out more information," Home Secretary David Blunkett said.
John Reid, chairman of the governing Labor Party, said the world faced a terrorist threat on the scale of the Sept. 11 attacks, but later said he did not mean that the threat at Heathrow was of that magnitude.
"This is about a threat of the nature that massacred thousands of people in New York," Reid said during a visit to Manchester, responding to a question about the security measures in the London area.
But Reid said later that he was referring to the overall phenomenon of international terrorism, not to a specific threat against Britain.
"I was asked, what was my response to those people who said that what was going on at Heathrow and elsewhere was all part of a public relations exercise, a spin," Reid said in an interview with British Broadcasting Corp. radio.
"And I said that I didn't think that was even worthy of an answer -- that we were dealing with a huge problem, the nature of the phenomenon of international terrorism which gave us things like the twin towers in New York.
"And the suggestion that any government would use that sort of subject amd phenomenon for spin and public relations I thought was beneath contempt," Reid said.
He said his comparison to Sept. 11 was "misinterpreted, and I can understand why, by someone thinking that I had said that the scale of the threat at Heathrow was the same as the scale of the threat in New York. That was not said, it was not meant."
Light tanks and hundreds of troops were deployed at Heathrow Airport west of London Tuesday, when police warned that Usama bin Laden's Al Qaeda network might try attacking the British capital.
Asked whether the security measures were excessive, Reid said: "I am not even going to take seriously those people who suggest this is part of some sort of game."
London Mayor Ken Livingstone said that any attack against the capital would probably involve a small device.
Earlier Wednesday, the Metropolitan Police said "nothing had changed" since they brought in 450 soldiers to boost security at Heathrow, Britain's busiest airport, the day before.
Police also added patrols in central London in response to "a potential threat to the capital" amid terrorism fears ahead of a possible war on Iraq.
Police didn't specify the nature of the threat or how long the operation would last, but warned the Al Qaeda group might try attacking London at the end of this week's Muslim festival of Eid al-Adha.
Prime Minister Tony Blair personally authorized the security operation, his spokesman said Tuesday, adding that the measures were being taken in response to a "specific threat."
Britain is Washington's main ally in its confrontation with Iraq and the new security measure comes after America on Friday raised its terror alert from yellow to orange.
"This is part of our ongoing operations at the airport which aim to reassure the public that every possible step is being taken to make sure people are safe while traveling," said Chief Inspector Martin Gaffney.
Beginning Monday night, police increased patrols and randomly stopped cars for inspection.
"We decided to boost the policing presence to demonstrate our commitment to ensuring that people can travel safely," Gaffney told British Broadcasting Corp. radio.
Blunkett said Blair and the cabinet learned of the threat to London on Monday.
"We decided we needed to act on it and that was to put in place the preventative measures to pre-empt any action that was threatening us," he said. "We hope we can get through the next few days without an incident. I hope we can."
Metropolitan Police Commissioner Sir John Stevens on Tuesday urged the public to remain calm.
"I don't want people to panic, people should not be alarmed, they should be alert," Stevens said. He added that the security operation was for the whole of London, although it was most visible at Heathrow.