NATO has accused the Syrian regime of firing Scud-style missiles at rebels, amid Russian criticism that the West's "dangerous" stance risks bringing chaos to the country and beyond.

North Atlantic Treaty Organisation chief Anders Fogh Rasmussen on Friday called the Syrian army's use of missiles against rebels an act of desperation.

"I can confirm that we have detected the launch of Scud-type missiles; we strongly regret that act," Rasmussen said. "I consider it an act of a desperate regime approaching collapse."

The latest launches were detected on Thursday, a source close to NATO said, and that was corroborated by an activist in the rebel-held town of Marea in the northern province of Aleppo.

Abu Hisham told AFP he had been awakened to "the sound of a very loud explosion. It was raining heavily and there were many clouds, so we knew it was unlikely to be aerial bombardment."

"The first missile fell outside Marea. Had it hit the town it would have caused a massacre. The second, my friends told me, fell outside (the nearby town of) Tel Refaat."

Russia's Foreign Minister Sergei Lavrov on Friday denounced the West's "dangerous" stance in support of Syrian rebels seeking to unseat President Bashar al-Assad.

"Our Western colleagues have started dividing terrorists into 'bad' and 'acceptable.' That is very dangerous," he said in an interview with the English-language Russia Today channel.

Lavrov reiterated Moscow's position that the Syrian people should be allowed to decide their own destiny without outside agencies seeking to help oust the regime.

"We are not in the business of regime change," he insisted.

Russia's President Vladimir Putin said that Moscow, one of the last supporters of the Assad regime, wanted to avoid "chaos" in Syria, calling for political talks between all parties to take the war-torn country towards a democratic regime.

"We are interested in this because this is all very close to our borders. We really would not like to see any potential changes in Syria to lead to the chaos we are witnessing in other countries of the region," Putin stressed after an EU-Russia summit in Brussels.

For the second time in two days, Putin denied propping up Assad's regime and appeared to acknowledge the possibility of change, saying: "We do not advocate the government of Syria."

In Damascus, Palestinian refugees streamed back to the Yarmuk camp after a reported deal to keep it out of the conflict, following fierce clashes earlier this week and briefly on Friday.

An AFP correspondent heard sporadic shooting, and a main road was blocked with boulders to keep out cars, although a van full of passengers still entered through a side street.

The fighting forced about 100,000 of Yarmuk's 150,000-strong population to flee, with many taking refuge in Damascus parks and squares, said the UN Relief and Works Agency for Palestinian refugees.

Hours after they returned on Friday, fighting again flared in the camp for about an hour and a half, said the Syrian Observatory for Human Rights.

"The fighting pitted anti-regime Syrian and Palestinian rebels against members of the pro-regime popular committees," said Observatory director Rami Abdel Rahman.

The clashes were between fighters who had not withdrawn from Yarmuk despite a reported agreement after talks that began on Wednesday aimed at removing both rebel and government fighters from the camp.

Newspapers in neighbouring Lebanon said an agreement had been reached under the auspices of Mokhtar Lamani, the representative of UN-Arab League peace envoy Lakhdar Brahimi.

The UN's World Food Programme said it was to start providing food to 125,000 "vulnerable Palestinians and displaced Syrians" in and around Yarmuk.

Elsewhere, violence raged in flashpoints across Syria, with the Britain-based monitor saying at least 82 people were killed.

And a rebel attack on an electricity pylon caused a power outage in several areas of Damascus, state television said.

Despite the violence, protesters took to the streets in several anti-regime areas, renewing calls for the fall of Assad's regime, it said.

Last week a former Syrian officer said regime forces had fired Scuds, despite the government denials.

Former first lieutenant Aaraba Idriss, who defected 10 months ago and has joined the rebels, said serving officers told him the army fired "Golan-1" missiles, either Russian-made or Russian modified," with a range of up to 300 kilometres (180 miles).