Updated

Detained terror suspects told interrogators that Al Qaeda's top leaders approved a plot to blow up planes from Britain to the United States, a senior Pakistani intelligence agent said Thursday.

Some of the suspects said No. 2-ranked Ayman al-Zawahiri probably authorized the plan, said the official, who spoke to The Associated Press on condition of anonymity due to the sensitivity of the investigation.

Usama bin Laden's Egyptian-born right-hand man, believed to be hiding on the Pakistan-Afghan border, is the highest-ranked Al Qaeda leader named to date in relation to what authorities called a plot to destroy trans-Atlantic jetliners with liquid explosives.

Pakistani intelligence officials have said the would-be London plane bombers wanted to carry out a large, Al Qaeda-style coordinated attack to mark the fifth anniversary of the Sept. 11 attacks in the United States, but were too "inexperienced" to carry it out.

At least seven suspects were arrested in Pakistan, including British national Rashid Rauf, who Pakistani authorities say had been in contact with Al Qaeda figures in Pakistan and Afghanistan to prepare for the attacks. Another 23 people have been arrested in Britain, including Rauf's brother, Tayib. Initial reports from Pakistani intelligence agents indicated as many as 17 people were arrested.

Pakistani authorities said Rashid Rauf, who was arrested in the eastern Punjab city of Bhawalpur, had belonged to the outlawed Pakistani militant group, Jaish-e-Mohammed, but later aligned himself with Al Qaeda.

The Taliban-linked group, which has fought Indian forces in Kashmir, denied that Rauf had ever been a member.

The senior Pakistani intelligence official said there was no evidence that Jaish-e-Mohammed was linked to the foiled terror plot.

Hafiz Mohammed Sohaib, who teaches at an Islamic school in Bhawalpur, said Rashid Rauf married one of his sisters. Sohaib's other sister is married to the brother of Maulana Masood Azhar, the wanted head of Jaish-e-Mohammed.

Pakistani officials, who declined to be identified because of the sensitivity of the investigation, said they were searching for three more suspects believed to be at large in Pakistan — a Briton of Afghan descent, an Eritrean and a Pakistani.

Pakistani authorities have yet to charge any of the detainees. Anti-terror laws permit the state to hold people for up to three months before filing official complaints.

Authorities in Britain said negotiations are continuing with Pakistan over Rashid Rauf's extradition and that talks are likely to last several days.