HAMBURG, Germany (AP) -- The Islamic militant whose disclosures under U.S. interrogation in Afghanistan triggered Europe's terror alert is an old friend of a man convicted in the 9/11 attacks and, as the strikes were being planned, frequented the same mosque where the Hamburg-based plotters often met, officials say.
Hamburg security officials in August shuttered the Taiba mosque, known until two years ago as al-Quds, because of fears it was becoming a magnet for homegrown extremists who, unlike foreigners, could not be expelled from the country.
Ahmad Wali Siddiqui, a 36-year-old German of Afghan descent arrested by the U.S. military in July in Afghanistan has emerged as the latest link between Germany and al-Qaida's worldwide terror campaign. Siddiqui is believed to have been part of the Hamburg militant scene that also included key 9/11 plotters.
Intelligence officials say he was a friend of Mounir el Motassadeq, who was convicted by a German court in 2006 of being an accessory to the murder of the 246 passengers and crew on the four jetliners used in the 2001 terrorist attacks, and also frequented the al-Quds mosque.
Motassadeq was found to have aided suicide hijackers Mohamed Atta, Marwan al-Shehhi and Ziad Jarrah by helping them keep up the appearance of being regular university students - paying their tuition and rent - though it was never established whether he knew of the planned timing, dimension or targets of the attacks.
"Siddiqui is a long-term member who has been a friend of Motassadeq since 1997," said a senior intelligence official, who spoke on condition of anonymity due to the sensitivity of the issue.
U.S. officials say Siddiqui provided details on the alleged al-Qaida-linked plots against European capitals that prompted Washington to issue a travel alert for Europe over the weekend, followed by other countries such as Japan that issued similar warnings.
The suspected plot is believed to have involved plans for coordinated Mumbai-style attacks in European capitals - and prompted authorities to heighten surveillance at iconic sites such as London's Buckingham Palace Paris' Eiffel Tower.
However, German officials including Interior Minister Thomas de Maiziere warned against being "alarmist" and stressed there currently are no concrete indications of an imminent attack.
Siddiqui left Hamburg in March 2009 together with a group of 10 other jihadis known to German intelligence officials as the "The Tourist Group" to seek paramilitary training at a terror camp in Pakistan's lawless border region with Afghanistan, German authorities said.
The group, which included two women, met in the al-Quds mosque before they decided to leave for Pakistan and Afghanistan. The prayer house had served as gathering point for some of the Sept. 11 attackers before they moved to the United States to attend flight schools in 2000, authorities say. Atta, al-Shehhi and Jarrah attended the mosque when they lived and studied in Hamburg.
Following the Sept. 11 attacks, the mosque became a magnet for so-called jihad tourists - Muslims from out of town who bragged about having worshipped at the same mosque where once the suicide hijackers had gathered for prayer.
"Young people came because they wanted to pray on the same carpet that Mohammed Atta had already used for his prayers," the intelligence official said.
Other members of Hamburg's 130,000-strong Muslim community largely rejected the extremist beliefs preached at al-Quds.
"They had the strong expectation to find the true Islam and campfire romance in North Waziristan, but then discovered that they were in the midst of a dirty war," Norbert Mueller, who represents the Schura Association of Islamic Communities in Hamburg, told The Associated Press.
That sentiment was echoed by the vast majority of Hamburg's Muslims, who strongly deplore the fact their city's name is once again linked to Islamic extremism.
"Those extremists ... perverted our religion. That has nothing to do with Islam," said Ahmet Yazici, the deputy head of the Alliance of Islamic Communities in Northern Germany.
Authorities insist they have the city's estimated 200 extremist Muslims - including 45 al-Qaida followers - under surveillance and have sought to downplay Hamburg's role in the international terror scene.
"Hamburg is a big city and you have a few radicals, but it is not the worldwide center of jihad," said the intelligence official.
While the al-Quds mosque was open, it was a convenient place for authorities to monitor the extremist scene. Several of those who frequented it were expelled. But as an increasing number of radicals held German citizenship, authorities moved to gather enough evidence to ban the extremist group behind the mosque, forcing its closure.
"We couldn't hinder the mosque attracting young people. That's why we finally decided to close down that black hole," the official said.
The imam of the Taiba mosque at the time of its closure was Mamoun Darkazanli, who was questioned following the 2001 attacks after it emerged that he moved in some of the same circles as the hijackers - even appearing on a 1999 wedding video with al-Shehhi and Jarrah.
In October 2004, he was arrested in Hamburg on a Spanish warrant accusing him of involvement with al-Qaida. German authorities said then that Spanish authorities alleged he was "one of the key figures of the al-Qaida terror network" and "the permanent contact person and assistant of Osama bin Laden in Germany," as well as a financier for bin Laden.
His extradition was blocked by Germany's high court and he was eventually released. In 2006, German prosecutors closed their own investigation of him, saying there was insufficient evidence to show that Darkazanli still supported al-Qaida.
Darkazanli, who intelligence officials still consider "a jihad leader," has denied any links to bin Laden or the attacks. He did not answer a message left at his Hamburg apartment.
He lives freely in a wealthy Hamburg neighborhood, as his alleged support for a foreign terrorist organization dates back to pre-2002, such activity was not criminal under Germany law.
Meanwhile, Pakistani officials said this week that eight German militants were killed in a U.S. missile strike in North Waziristan, although Germany has said it has not received any evidence its citizens were killed.
A website known for posting radical Islamist propaganda said the drone strike killed 10 locals, but only four militants - two Tajiks and two Germans.
A Turkish-language posting on the Jihad Media website said one of them was Abu Askar Al Almani from the Islamic Movement of Uzbekistan - another member of Hamburg's "Tourist Group."
German authorities couldn't immediately confirm the authenticity of the video or its content, though a German security official who spoke on condition of anonymity due to the sensitivity of the issue said the way the video was distributed suggests it is authentic.
But the Interior Ministry and the Foreign Ministry in Berlin said they still have no reliable information on the identity of those allegedly killed.
The Iranian-born Shahab D., alias "Abu Askar," has appeared in at least two Islamist propaganda videos. In one, he is seen wielding a sword and praising the jihad.
Germany's Federal Criminal Police Office has said that there are indications that some 220 people have traveled from Germany to Pakistan and Afghanistan for paramilitary training, and "concrete evidence" that 70 of those had done so. About a third of them are thought to have returned to Germany.
Pakistani intelligence officials have said they believe between 15 and 40 Germans are in the border area - a lawless region where many top al-Qaida Arab leaders are believed to be hiding, including bin Laden and his Egyptian deputy, Ayman al-Zawahri.
Siddiqui and others from the Hamburg group went there to join the Islamic Movement of Uzbekistan, intelligence officials said. The militant group is fighting U.S. and coalition forces across the border in Afghanistan and it is said to have links with al-Qaida.
A German diplomat on Sunday met for the first time with Siddiqui, but Germany's intelligence or police authorities have not had access to him and have no independent way of evaluating what he told U.S. interrogators about the planned attacks in Europe.
"But we strongly assume that the basic story is accurate: al-Qaida and other groups are trying to recruit Europeans and send them back to carry out attacks," the intelligence official said.