Thousands of Palestinians returned on Thursday to a refugee camp in Damascus that has become a battle ground, as UN investigators warned of an openly sectarian conflict that threatens whole communities.
Meanwhile, the UN General Assembly voted overwhelmingly to rebuke Syria, alongside Iran and North Korea, for human rights abuses.
Four days on from a first air strike on Yarmuk refugee camp, "thousands of Palestinians walked across army checkpoints at the entrance to the camp to return home, rather than sleep outside in the cold and under the rain," an aid worker in the camp said.
According to one resident and amateur video posted online, refugees sang traditional Palestinian songs, and chanted: "We are returning to Yarmuk camp".
Another resident said most the fighters of the rebel Free Syrian Army that had been deployed in their thousands days earlier had pulled out of Yarmuk.
"There are a couple of fighters in each alley way, but they're drinking tea and smoking the nargileh (water-pipe)," the resident told AFP.
Khaled Meshaal, leader of the Palestinian Islamist group Hamas,called on international peace envoy Lakhdar Brahimi, on Arab League Secretary General Nabil al-Arabi and others to "ensure Yarmuk and other Palestinian camps are spared," a statement said.
In Geneva, the United Nations Relief and Works Agency for Palestine refugees (UNRWA) said as many as 100,000 Palestinians may have fled Yarmuk in the past few days.
The dramatic turn of events in Damascus in recent days was followed by UN findings that Syria's conflict has become "overtly sectarian".
"As the conflict drags on, the parties have become ever more violent and unpredictable, which has led to their conduct increasingly being in breach of international law," the UN Commission of Inquiry on Syria said in a report published on Thursday.
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After 21 months of conflict, which a monitoring group says has killed more than 44,000 people, "the dangers are evident," it continued.
"Entire communities are at risk of being forced out of the country or of being killed inside the country," it said, stressing that "with communities believing -- not without cause -- that they face an existential threat, the need for a negotiated settlement is more urgent than ever."
Minority groups such as Armenians, other Christians, Druze, Palestinians, Kurds and Turkmen had also been drawn into the conflict, the report said.
"However, the sectarian lines fall most sharply between Syria's Alawite community, from which most of the government's senior political and military figures hail, and the country's majority Sunni community, who are broadly... in support of the anti-government armed groups."
In a 193-state vote at the UN General Assembly, 135 countries voted in favour of a resolution slamming "grave" and "systematic" abuses in Syria, which came as a diplomatic blow for President Bashar al-Assad.
The Assad government has been accused of detaining thousands of opponents, often in secret, torturing many. The government has refused to allow a UN human rights council investigation into the country.
The UN called for an end to rights violations of human rights by all parties to the conflict.
While Moscow and Beijing both voted against the resolution, Russian President Vladimir Putin toold a press briefing: "We are not concerned about Assad's fate. We understand that the family has been in power for 40 years and there is a need for change."
But he made no call on Assad to step down and said it was for the Syrian people to decide their future through peaceful talks.
"What is our position? Not to leave Assad's regime in power at any price, but to first (let the Syrians) agree among themselves how they should live next," Putin said.