Mohammed Haydar Zammar (pictured in an undated file photo) has been arrested by Kurdish security forces in northern Syria and is now being interrogated, according to a senior commander

A Syrian-born German national accused of recruiting 9/11 terrorists has been arrested while fighting in Syria, according to a senior commander.

'Mohammed Haydar Zammar has been arrested by Kurdish security forces in northern Syria and is now being interrogated,' a top Kurdish commander said, without providing further details.

Zammar, a career extremist in his mid-fifties, was mentioned several times in the 9/11 Commission's report, which said he encouraged worshippers at a Hamburg mosque towards terrorism and alleged 9/11 financer Ramzi Binalshibh.

The report also claimed he 'fought in Afghanistan and relished any opportunity to extol the virtues of violent jihad' and took credit for influencing Binalshibh, 9/11 ringleader Mohammed Atta and others in the 'Hamburg Group' following the attack.

Atta hijacked American Airlines Flight 11, which crashed into the North Tower of the World Trade Center in New York.

He was detained in Morocco in December 2001 in an operation involving CIA agents and was handed over to the Syrian authorities two weeks later.

Zammar was mentioned several times in the 9/11 Commission's report, which said he encouraged worshippers at a Hamburg mosque towards terrorism. Pictured: The hijacked United Airlines Flight 175 flies towards the South Tower of the World Trade Center in New York

The report also claimed he 'fought in Afghanistan and relished any opportunity to extol the virtues of violent jihad' and took credit for influencing Binalshibh, (left) and 9/11 ringleader Mohammed Atta (right). Both photos are undated

A Syrian court sentenced Zammar to 12 years in prison in 2007 for belonging to the Muslim Brotherhood, a charge that at the time could have resulted in the death penalty.

But conflict broke out in Syria four years later, and many hardline Islamist prisoners were released from jail or broke free and went on to join jihadist groups fighting in the war.

Al-Qaeda operated a branch in Syria known as Al-Nusra Front, but the affiliate has since claimed to have broken off ties.

The Islamic State jihadist group also rose to power in the country's north and east, but a US-backed alliance has ousted it from swathes of its onetime 'caliphate.'

Binalshibh is currently imprisoned in Guantanamo Bay (pic on March 30, 2010) where he has been held since September 2006

The Syrian Democratic Forces, a coalition of Arab and Kurdish fighters, has caught several foreign members of IS in Syria in recent months, particularly since the SDF captured the northern city of Raqqa from the jihadists.

The Kurdish commander who spoke to AFP on Wednesday declined to say whether Zammar had been actively fighting as a member of an extremist group in Syria.

The Pentagon said it had nothing to confirm on Zammar's capture but was looking into it. It was not clear what group he had been fighting for.