The Bank of England, Britain's central bank, said Friday it had frozen the accounts of 19 of 24 men arrested in Britain on Thursday over the allegations, and publicly released their names.

Separately ABC News quoting Pakistani officials identified the ringleader of the bomb plot as Matiur Rehman, said to be a 29-year-old Al-Qaeda commander accused of involvement in plots to kill President Pervez Musharraf.

He was said to be missing along with five others, ABC said, adding that Rehman was known to be planning a "terror spectacular" to mark the fifth anniversary of the September 11 attacks in the United States.

Al-Qaeda has already been fingered as a possible culprit behind the plot. Pakistan has arrested dozens of Al-Qaeda militants, including the capture three years ago of Khalid Sheikh Mohammed, the alleged mastermind of 9/11.

But Musharraf has faced international criticism for failing to crack down on militancy, despite surviving three assassination attempts by extremists linked to Al-Qaeda.

Pakistan came under pressure after the July 7, 2005 suicide attacks on the London transport system when it emerged that some of the British-born bombers had attended Islamic religious schools, or madrassas, here.

However, Britain's Reid thanked Pakistan for its help in uncovering the airliner plot.

"We are very grateful for all the help and cooperation we have received from our international partners, including Pakistan, and I would like to thank them for the assistance they have given us," he told a news conference in London.