Beirut: The head of the UN investigation into the assassination of former Lebanese premier Rafik Hariri wants to step down.

A statement issued by Detlev Mehlis' spokesperson said that he wants to leave his post after he has submitted his report in two weeks' time.

"I have committed myself to the U.N. until the 15th of December; that was very clear from the beginning," the New York Times newspaper reported Mehlis as saying in an interview which was published on Tuesday.

"That will be the end from my personal mandate. I have to go back and I will go back to my job that I like. I never asked for this assignment. I agreed to be available up to seven months."

Prime Minister Fouad Siniora told Annan in a phone call on Saturday that the Lebanese government wanted the inquiry to continue for six months after its December 15 deadline, and be open to further extensions, a statement from his office said.

Mehlis' interim report in October cast suspicion on senior Syrian officials and suggested the assassination was planned by top security officials in Damascus and their Lebanese allies.

Syria has dismissed those accusations as politically motivated. Diplomatic sources said on Sunday that five Syrian officials summoned by Mehlis had left Damascus for Vienna, where UN investigators will start questioning them on Monday.