North Atlantic Treaty Organisation chief Anders Fogh Rasmussen 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."
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The clashes were between fighters who had not withdrawn from Yarmuk despite a reported agreement after talks that began on Wednesday aimed at removing both rebel and government fighters from the camp.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 President Bashar al-Assad's regime, it said.
Russian President Vladimir Putin said Moscow does not want "chaos" in Syria -- 21 months into an anti-regime revolt that monitors say has claimed more than 44,000 lives -- and that it looked forward to seeing a democratic regime there.
"We will try to pursue the public order in Syria and look forward to a democratic regime in Syria because this country is close to our borders," he said at a news conference on the sidelines of an EU summit in Brussels.
"We wouldn't like chaos in that country," he added. "Everyone is interested in stopping the violence and the bloodshed."
For the secont 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."
He insisted, however, that a solution must be found among all parties at the negotiating table to take into account the views "of all the citizens."
On Thursday, Putin said Russia was not concerned about Assad's fate, but "we understand that the family has been in power for 40 years and there is a need for change."
The Syrian regime has fired Scud-style missiles at rebels, NATO said, as Russia raised the alarm over the risk of chaos in Syria and Palestinians forced to flee their Damascus camp returned.