The United States repatriated a suspected al-Qaida operative to Saudi Arabia from Guantanamo after assessing that he no longer posed a threat to US national security, military officials announced on Wednesday.

Ghassan al Sharbi, a Saudi engineer, was detained in Faisalabad, Pakistan over two decades ago.

He was a suspect in the September 11, 2001 al-Qaida attacks but never charged, was released from the Guantanamo military prison after he was deemed no longer enough of a threat to the US to be held in military detention, according to officials.

The Department of Defense (DoD) stated that Al Sharbi's repatriation was "subject to the implementation of a comprehensive set of security measures including monitoring, travel restrictions and continued information sharing."

Never charged

Al Sharbi's connection to the 9/11 attacks stems from his education in aeronautical engineering at an Arizona university and attending flight school with two of the al-Qaeda hijackers involved in the plot.

The US previously claimed al Sharbi fled to Pakistan after the September 11 attacks for training in bomb-making.

Al Sharbi was arrested in Pakistan in 2002, reportedly tortured in custody, and eventually sent to the Guantanamo military prison.

While the US military considered charging him and several others, they ultimately dropped the charges in 2008.

Despite not being charged, al Sharbi remained detained as an enemy combatant in the military prison located in the US Navy's base at Guantanamo Bay, Cuba, without approval for release.

Guantanamo numbers decrease

The release of al Sharbi from the Guantanamo military prison is a part of the continuing efforts to release detainees who are no longer facing prosecution.

The review board recommended transferring al Sharbi to Saudi custody, contingent on the implementation of rigorous security measures.

Saudi Arabia, the country from which most of the 9/11 hijackers originated, has long maintained facilities to detain and rehabilitate extremists.

With al Sharbi's release, 31 detainees remain at Guantanamo, down from a peak of nearly 800.

ss/jsi (AP, AFP, dpa)