BEIRUT, Lebanon - The former head of the wiretapping unit for Lebanon's army was questioned Thursday by members of a United Nations commission investigating the assassination of former Prime Minister Rafik Hariri, officials said.

Col. Ghassan Tufeili was detained by Lebanese security agents on orders from the head of the U.N. investigating team, German prosecutor Detlev Mehlis. Security agents also raided his home.

He was questioned for five hours before being released, said the officials, who spoke on condition of anonymity because they were not authorized to speak to journalists. They declined to give further details.

Tufeili was dismissed in May, as were other pro-Syrian chiefs of Lebanese security agencies, and moved to an administrative post.

The then-opposition had accused pro-Syrian security officers of negligence and a coverup in the Feb. 14 killing of Hariri. Four other former pro-Syrian security chiefs were arrested in August after they were accused of complicity in Hariri's death by the U.N. investigating team.

Hariri died in a truck bombing in Beirut that killed 20 other people. His death sparked a wave of protests by Lebanese, many of whom accused Syria's government of being behind the assassination.

A report by Mehlis released last month implicated top Syrian and Lebanese intelligence officials in Hariri's death. While the new Lebanese government praised the report, Syria rejected its findings as false, unprofessional and politicized.

Syria has repeatedly denied any role in Hariri's death but was forced to withdraw its military from Lebanon in April under international pressure. (AP)