“I know how difficult it is – how nearly impossible,” Brahimi told the BBC in an interview published on Monday. “And we are not doing much. That in itself is a terrible weight.”

Mr. Brahimi is taking over the peace-facilitation role which has been carried out since February by former UN Secretary-General Kofi Annan who stepped down at the end of August. The former UN secretary general complained about the lack of international support shown for his six-month campaign to make President Bashar al-Assad and opposition fighters end their hostilities.

The former UN secretary general had called for sanctions against Assad to make him comply with the plan, but Russia and China have blocked three sanctions resolutions since the beginning of the 18-month old war which activists say has left more than 25,000 dead.

Jihad Makdissi, a spokesperson for Assad’s embattled government, announced Brahimi would “soon” travel to Damascus, expressing confidence that “he will listen to us.”

Meanwhile, Syrian troops killed more than 20 people Sunday in a blistering raid on a central village, a watchdog said, while twin blasts rocked Damascus and a town near Syria’s second city Aleppo was hit by air strikes, according to Reuters.

The Syrian Observatory for Human Rights said it expected the death toll to mount from the army offensive on Al-Fan village in Hama province, one of the main arenas of conflict in the more than 17-month uprising, according to Reuters as horrific images shot and posted on YouTube by activists in Al-Fan showed a long row of bodies shrouded in white cloths, laid out on the ground surrounded by scores of weeping men, women and children.

State news agency SANA said all of those killed during the Al-Fan clashes were from “an armed terrorist group that was attacking citizens and security forces.”

At the same time, Human Rigths activists  have expressed growing concern about deteriorating humanitarian  conditions in areas of Aleppo and third city Homs.