Al-Assad's decision on Saturday comes after a UN investigator implicated top Syrian and Lebanese security officials in al-Hariri's 14 February killing and accused Damascus of not cooperating with the inquiry.

"President Bashar Assad issued a decree ... to form a special judicial committee headed by the prosecutor-general and comprising the military prosecutor and a judge, to be named by the justice minister, to question Syrian civilians and military personnel on all matters relating to the UN investigation commission's mission," according to the SANA news agency's report.

Fill the gaps

On Tuesday, chief UN investigator Detlev Mehlis urged Syria to conduct its own investigation over the coming weeks to help fill the gaps over who orchestrated the act.

Mehlis urged Syria to conduct an
investigation into the killing

Al-Assad's announcement could be aimed at deflecting heat over US and UN accusations that it has not been fully cooperating with the world body's efforts to find al-Hariri's killers.

The presidential decree also said the new committee would cooperate with the Mehlis investigation commission and Lebanese judicial authorities who had been aiding the UN inquiry and charged four pro-Syrian Lebanese generals in connection with al-Hariri's killing.

Syria has sharply criticised the UN report but expressed willingness to cooperate with the Mehlis investigation, which has been extended until 15 December.

UN resolution

The United States, France and Britain are promoting a Security Council resolution to be discussed on Monday threatening tough sanctions if Syria fails to cooperate with the UN inquiry.

The resolution requires Syria to detain any official or civilian that UN investigators consider a suspect in al-Hariri's killing and let the individual be questioned either outside Syria or without Syrian officials present.

The United States has said that will include calling al-Assad himself for questioning. The Syrian leader has not accepted UN requests to be interviewed in the investigation.

Russia, another permanent Security Council member, has expressed opposition to imposing sanctions on Syria.