And President Bashar al-Assad has sent letters to UN Security Council members explaining Syria's position, ahead of a briefing to the 15-nation body on Tuesday by the German judge who wrote the report, Syrian state television reported without giving details.

Detlev Mehlis's report is "full of contradictions and has distorted the truth and the facts," said the National Progressive Front, which groups eight parties headed by al-Assad's Baath. 

"The parties trying to harm Syria will use the political issues contained in the report ... which is based on testimony from people who lack all credibility and known for their hostility to Syria," the group said in a statement.

Damascus has tried to cast doubts on the credibility of the UN report which implicates Syrian security officials in the murder since Mehlis released the results of his inquiry on Thursday at the United Nations in New York. 

The Front accused the UN commission headed by Mehlis of having "distorted the testimony of Syrian officials" during interviews carried out last month. 

It said Syria had cooperated in full with the commission, contrary to the report, which said it had cooperated only "to a limited degree" after initially hesitating to help.

"All this shows that the commission of inquiry was influenced by forces which want to harm Syria, weaken it and make unfounded accusations as part of political motives linked to the plans being hatched for the region."