Two weeks after an alleged plot to blow up U.S.-bound airliners was thwarted in Britain, Pakistani authorities have screwed tight the faucet that had trickled intriguing details from their investigation.

Mystery surrounds the role played by "key suspect" Rashid Rauf, a Briton with dual Pakistani nationality who has family ties to a notorious Pakistani militant. Pakistani authorities allege Rauf communicated between an Al Qaeda mastermind in Afghanistan and the plotters in Britain.

Britain has yet to confirm Al Qaeda's involvement in the plans to bomb as many as 10 U.S.-bound aircraft. On Wednesday, it released Rauf's brother Tayib without charge. The Home Office in London refused to say Thursday whether it was still seeking Rashid Rauf's extradition.

Rauf, in his mid-20s, is the only one among the at least seven suspects arrested in Pakistan to have been named. He is being interrogated at a high-walled Pakistani intelligence headquarters in the garrison city of Rawalpindi, near the capital Islamabad.

It's unclear if he or the other suspects have been charged with any offense.

The lack of transparency is characteristic of terror cases in Pakistan, which has netted most of the top Al Qaeda figures captured since the Sept. 11, 2001, attacks on America. It contrasts with the legal process pursued in Britain, where despite tight control on information from the investigation, authorities named two dozen suspects soon after their arrest Aug. 10.

So far, British authorities have charged 11: eight with conspiracy to murder and preparing to commit terrorism, and three others with lesser offenses, including failing to disclose information.

Under Pakistani law, authorities can hold any terror suspect for up to a year without charge. Such a detention must be approved by a panel of judges. In practice, suspects in the custody of intelligence agencies have little or no recourse to the law.

"The difference between Britain and Pakistan is the absence of due process," said Samina Ahmed, South Asia project director for the International Crisis Group think tank.

"There's been very little information to come out, other than about Rauf, and I think that's because his links with some very prominent jihadi leaders were bound to come out in the open. It would have been impossible to keep it covered up," she said.

Rauf has ties by marriage to Masood Azhar, leader of an Al Qaeda-linked Pakistani militant group, Jaish-e-Mohammed. Rauf was arrested Aug. 9 in the Punjab town of Bhawalpur, where he had settled and where the outlawed group has a strong presence.

A senior Pakistani government official, who like the intelligence official spoke on condition of anonymity because of the case's sensitivity, described Rauf as a "transmitter of messages" between the unnamed Al Qaeda mastermind in Afghanistan and plotters in London.

The official said there was as yet no established link with Pakistani militant groups to the plot.

To many observers in Pakistan that stretches credibility, and could explain authorities' reluctance to divulge more details about the other suspects, even their nationalities.

A Pakistani intelligence officer said Rauf had been monitored for five or six months, and within two days of his arrest had given investigators a full picture of the plot. The information was shared with Britain and the U.S., whose leaders later praised Pakistan's role thwarting the plan.

President Gen. Pervez Musharraf, a key Western ally, has been robust in fighting Al Qaeda and has taken steps to reel in militant groups that emerged here during the U.S.-backed jihad against the Soviet occupation of Afghanistan in the 1980s and later, the Pakistan-endorsed fight against Indian rule in Kashmir.

But the continued presence of dangerous militants in Pakistan and its failure to regulate religious schools that cultivate extremists has left this Islamic nation open to allegations that it remains a magnet for jihadists — such as the suicide bombers who killed 52 people on the London transit system in July 2005. Three of them visited Pakistan before the attacks.

Pakistan has also placed under house arrest Hafiz Mohammed Saeed, former leader of the outlawed Lashkar-e-Tayyaba group, which fights in Kashmir.

The government said his Aug. 10 detention was to prevent him from making a public address in Lahore on Aug. 12, but he has not been released, adding to the mystery surrounding Pakistan's investigations.

On Thursday intelligence agents took him away from his home in the city to an undisclosed location for questioning. Officials refused to disclose the reason.