Britain's Home Secretary John Reid warned Sunday that another attempted terrorist attack on Britain was "highly likely" after police said they had thwarted a plot to blow up transatlantic airliners.

"We think we have the main suspects in this particular plot," Home Secretary Reid said, "but there could be others out there, perhaps people we don't know."

"It is highly likely there will be another terrorist attempt," he told BBC television. "The threat of a terrorist attack in the United Kingdom is still very substantial."

Reid said at least four plots had been thwarted since July last year when four Islamist suicide bombers killed 52 people on London buses and trains, and he did not deny media claims that police were hunting up to 25 terrorist cells in Britain.

Reid said that the plots would have led to significant loss of life and indicated that up to two dozen terror investigations were currently being pursued, confirming reports that police were hunting that number of terror cells in Britain.

"I'm not going to confirm an exact number but I wouldn't deny that that would indicate the number of major conspiracies that we are trying to look at," Reid said.

Regarding Thursday's terror raids, a Metropolitan Police spokeswoman said Sunday that enquiries were ongoing and searches continuing while 23 suspects remained in custody.

Reid added: "We think we have the main suspects in this particular plot."

"I have to be honest and say on the basis of what we know, there could be others out there... so the threat of a terrorist attack in the UK is still very substantial."

Meanwhile, the global investigation into last week's alleged plot has turned increasingly to Pakistan and Osama bin Laden's Al-Qaida network, amid fears that worse plans could be afoot.

"Summer of War," read a two-page spread in the News of the World, which is Britain's biggest-selling tabloid.

"Britain is facing a horrifying Summer of War blitz from Muslim terrorists and police fear last week's foiled airline plot was just the beginning," the newspaper reported.

Photographs of British Al-Qaida suspect Rashid Rauf appeared across the British media over the weekend after Pakistan authorities claimed he was a "key person" in the alleged plot.

Meanwhile, the Sunday Times newspaper in London said one of the suspects under arrest could be "Al-Qaida's leader" in Britain. He was not named.

In Pakistan, two senior officials said that Britain's intelligence services had asked their Pakistan counterparts to trail Rauf after he entered the country. He was arrested on August 4 in the eastern city of Bahawalpur.

"When they interrogated Rauf, he broke. He told them what we believe was not even in the knowledge of the US and the British that they were actually planning to blow up airliners," one of the officials said.

"When they had finished interrogating him for three or four days then they co-ordinated this information with the British authorities and they carried out the arrests in Britain."

Police said on Thursday they had foiled a plot by would-be suicide bombers to blow up simultaneously up to 10 airlines flying to the United States.

Disclosure of the alleged plot to smuggle bombs on aircraft disguised as drinks immediately brought drastic new security measures and chaos at airports on both sides of the Atlantic.

British Airways cancelled 30 percent of its flights from London's Heathrow airport Sunday in a growing row with airport authorities over how to handle tougher security.

Four days after police said they had thwarted the alleged plot, airlines warned that cancellations and disruptions showed no sign of easing.

In the blame game that erupted, British Airways called on the British Airports Authority (BAA) to increase resources with chief executive Willie Walsh complaining: "BAA is unable to provide a robust security search process and baggage operation."

Budget airline Ryanair also said airports could grind to a halt unless the government took action to reduce the passenger backlog, suggesting police and army reserves should help carry out searches.

But BAA's chief at Heathrow, Tony Douglas, said that if extra searches were maintained, long queues and cancellations were inevitable. "They're not sustainable measures," he said.

"I don't know how long it's likely to go on," he told BBC television.

A police spokesman said the suspects had been plotting "mass murder on an unimaginable scale." Britain has named 19 of those arrested, who were aged from 17 to 35.

(China Daily August 14, 2006)