KABUL, Afghanistan – A top Al Qaeda strategist with a $5 million bounty on his head and followers from Afghanistan to Europe has been captured in Pakistan, an American law enforcement official confirmed.

Mustafa Setmarian Nasar, who once wrote a 1,600-page autobiographical book on ways to attack Islam’s enemies, has been flown out of the country after being interrogated by Pakistani and American authorities, Pakistani officials told the Associated Press yesterday. They did not specify where he was taken.

Terror analysts said Mr. Nasar’s capture has dealt a blow to Al Qaeda and other militant movements he aided through his virulent anti-Western writings and weapons training. His movements have been traced to Sudan, Afghanistan, Iran, Iraq, Syria, and two European capitals.

A 47-year-old Syrian-Spanish national, Mr. Nasar was seized in the southwestern Pakistani city of Quetta in November 2005, the American official, who declined to be identified because of the sensitivity of the issue, said. Mr. Nasar was arrested in a sting operation, which sparked a gunfight in which one person was killed, the official said.

The raid apparently took place November 1. At the time, Pakistani officials said they had captured two possible Al Qaeda suspects and a third man with ties to a Pakistani extremist group. Intelligence officials had said they were investigating whether one of the suspects was Nasar.

An Islamic ideologue wanted by American and Spanish authorities for terror-related activities, Mr. Nasar, “may have been turned over to the U.S.” after his capture, the American official told the AP late last week. He would not say where Mr. Nasar may have been sent, and American officials in Washington declined to comment yesterday.

Pakistani and American officials have long been tightlipped on the status of Mr. Nasar, described by the American Justice Department as a former trainer at Osama bin Laden’s camps in Afghanistan who helped teach extremists to use poisons and chemicals before the American-led invasion of this country after the September 11, 2001, attacks.

The Syrian native’s dual citizenship – he was married to a Spanish woman – and his Western appearance made him difficult to find. His looks could resemble an Irish pub patron – red hair, light skin, stocky build. When he grew out his beard, Mr. Nasar – whose aliases ranged from Abu Musab al-Suri to Blond Blond – blended into Islamic society.

Previous reports indicated his journey into extremism began in the 1980s when he joined radical groups including the Syrian Muslim Brotherhood, which has opposed the Syrian government and developed ties with terror groups.

By 1988, Mr. Nasar was with the mujahedeen fighting the Soviet invasion of Afghanistan, where he met Mr. bin Laden and became a leader of the Syrians associated with early Al Qaeda, Spanish court documents say. When Mr. bin Laden moved his operations to Sudan in 1991, Mr. Nasar was known to visit.

Mr. Nasar deepened his European roots in the 1990s, living at various points in Madrid and London. Spanish police put him under surveillance in 1995, and Mr. Nasar packed up for London.

By late 1997, Mr. Nasar was running a training camp financed by Mr. bin Laden and keeping close contact with a Taliban leader, Mullah Omar, according to Spanish intelligence documents.

He was believed to be in Afghanistan at the time of the September 11 attacks, which he says were predicted by the Prophet Muhammad as events leading to victory for Islam.”The duty of jihad is a must until the end of days,” he wrote.

In 2004, Mr. Nasar released a 1,600-page book titled “The International Islamic Resistance Call.” He lists Islam’s enemies as “Jews, Americans, British, Russian, and any and all of the NATO countries, as well as any country that takes the position of oppressing Islam and Muslims,” according to a translation from the Washington based SITE Institute.

A Singapore-based terrorism expert, Rohan Gunaratna, said Mr. Nasar’s capture dealt a major blow to Al Qaeda and other radical Islamic movements as he was the “most prolific writer” of jihadi propaganda and had close links with extremists throughout Europe and South Asia.

“The ideologues are as equally important as the operational people and he was in close contact with very prominent figures with movements in different countries, particularly the North African region,” Mr. Gunaratna said.

American military officials aware of the detention of terror suspects at American prison facilities in Bagram, Afghanistan, and Guantanamo Bay, Cuba, said they had no immediate yesterday Tuesday on whether Mr. Nasar had been incarcerated at either jail.

But a senior Pakistani intelligence official told the AP Mr. Nasar had been flown out of Pakistan to an undisclosed destination “some time ago.”

“I only know that he is not here. But, I do know that Syrian authorities had also requested to get him back,” the official, who spoke on condition of anonymity because of sensitive nature of his work, said.

“He had been interrogated by us. He had been interrogated by our American friends,” said another Pakistani official, who also declined to be identified because of the secretive nature of his work. He said both Syrian and American authorities wanted to take Mr. Nasar into custody. Syrian authorities were not immediately available for comment.

Spanish authorities have previously said he may have played a pivotal role in the 2004 commuter train bombings in Madrid that killed 191 people. Among evidence, Spanish legal documents say an alleged cell member had Mr. Nasar’s bank account number in his notes at home.

In September 2003, Mr. Nasar was among 35 people named in an indictment handed down by a Spanish magistrate for terrorist activities connected to Al Qaeda. His exact role, if any, to either the Madrid or London bombings is unclear. He is also wanted for a 1985 attack on a restaurant near a military base close to Madrid airport that killed about 20 people – regarded as the first international Islamic terrorist attack in Spain.