Chief United Nations investigator Detlev Mehlis has complained that Syrian security figures interviewed in Damascus last month appeared to give only prepared responses. The Syrians had insisted that other officials attend the interviews.
"There shouldn't be a problem to meet with them as witnesses any time," the ambassador, Sami Khiyami, told Reuters on Friday.
"Mehlis can meet them completely alone, even choose a place in Damascus with a UN flag," he said, adding that the investigators would be free to produce their witnesses at the interviews, while keeping their identities secret if necessary.
The UN Security Council demanded last week that Syria cooperate fully with Mehlis's inquiry into the Beirut bombing that killed al-Hariri and 22 others or face "further action".
UN investigator Detlev Mehlis said
Syria failed to cooperate
Mehlis, who pointed to Syrian and Lebanese involvement in the assassination in an interim report in October, also accused Damascus of failing to cooperate properly with his mission.
Asked if Syrian President Bashar al-Assad would agree to be interviewed for the investigation, the ambassador said: "Let us not forget that he is the symbol of the country. Mehlis can ask to meet him, and I don't think there should be a problem, but there is no other way to meet the president but to ask for an audience."
Appeal for help
Meanwhile, a Syrian judicial committee investigating the assassination of al-Hariri has called for the public's help.
The committee urged anyone with information related to the 14 February bombing to come forth, Syria's official news agency said.
The Syrian public for the first time
was asked to help the UN inquiry
The call on Friday came a day after the committee, led by Syrian Prosecutor-General Ghada Murad, met for the first time since al-Assad ordered its creation on 29 October.
The decision to set up the committee followed suggestions by Mehlis for Syria to conduct its own inquiry into the assassination and work with the international investigation.
Murad, in a statement on Thursday reported by AFP, said the committee had begun its work by reviewing Mehlis's initial report to the Security Council last month and said it would coordinate with the UN investigation and Lebanese judicial authorities.
It called on anyone who has information on the killing to contact the Syrian committee.
On Friday, the committee announced its headquarters in Damascus and provided telephone and fax numbers as well as an email address.
The Syrian government has objected to Mehlis's report, saying his findings were inaccurate and "politicised".
It said, however, that it would continue to cooperate, because it was in Syria's interest to find al-Hariri's killers.
According to the decree issued by al-Assad, the committee - made up of Syria's prosecutor-general, the military prosecutor and a judge appointed by the justice minister - would question Syrian "civilians and military personnel on all matters relating to the UN investigation commission's mission".
The UN Security Council this week passed a unanimous resolution calling on Syria to fully cooperate with the UN inquiry and threatened punitive measures if it did not.