Fighting raged in Syria's second city Aleppo on Monday, with the army claiming to have secured much of a strategic district, as the United Nations denounced gross human rights violations by both sides.
Meanwhile, peace envoy Lakhdar Brahimi, who just spent four days in Syria, was to meet with the Syria "contact group" in Cairo as it seeks ways to end the bloodbath.
The district of "Midan is under the control of the army," a military official told AFP, in a report backed up by an AFP correspondent on the ground.
"We came back to our homes when we heard the army controlled Midan, but there was no electricity," a man said. "We waited for two hours and it didn't return. We will go back when it is fixed."
But not all areas were safe and an army checkpoint had been set up near the Midan police station, also retaken by the army, to prevent residents from returning to their homes in the so-called "fourth zone" of the district.
One man was turned away at an army checkpoint after being told there were still snipers in the area and it was not safe to enter.
The Syrian Observatory for Human Rights said at least four rebels were killed in fighting across the northern city, which has been the scene of battles since July 20.
A clash erupted near a building of the feared air force intelligence and rebels attacked a military post in New Aleppo as fighting also took place in other parts of the city, the Britain-based Observatory said.
The watchdog also reported that the army shelled the strongly pro-rebel district of Al-Hajar Al-Aswad in Damascus in preparation for storming it, with at least one person reportedly killed and several others wounded.
Shelling was also reported in several districts of the central city of Homs, which the army had claimed to have under its control.
In the northwestern province of Idlib, pro-regime gunmen killed three members of the same family in the town of Tamanaa, said the watchdog.
At least 64 people died nationwide on Monday, including 36 civilians, 15 soldiers and 13 rebels, the Observatory said, after 148 were killed the previous day.
The death toll from the 18-month conflict has risen to more than 27,000 people, says the Observatory, while the United Nations puts the figure at 20,000.
-- 'Gross rights violations' --
In Geneva, the head of a UN commission investigating rights abuses in Syria said they had soared dramatically in recent weeks and that the UN Security Council should take "appropriate action" against war criminals.
"Gross violations of human rights have grown in number, in pace and in scale," Paulo Sergio Pinheiro said, adding President Bashar al-Assad's regime and rebels, to a lesser extent, had committed war crimes.
"In a dramatic escalation, indiscriminate attacks on civilians in the form of air strikes and artillery shelling levelled against residential neighbourhoods are occurring daily," he said.
The indiscriminate use of weapons, he added, combined with a failure to protect civilians, reflected "a disturbing disregard for established rules of armed conflict."
Robert Serry, UN special coordinator for the Middle East peace process, too echoed similar views as he briefed the UN Security Council, saying: "Indiscriminate shelling of civilian areas by government forces with heavy weapons, tanks and air assets has increased."
For its part, Human Rights Watch called on the Security Council to refer the situation in Syria to the International Criminal Court.
"This is one measure that all Security Council members, including Russia, should find it easy to agree on if they are truly concerned about the violations committed in Syria," the New York-based group's Nadim Houry said in a statement.
"Extrajudicial or summary executions of detainees in the context of an armed conflict are war crimes, and may constitute crimes against humanity if they are widespread and systematic," the statement said.
In Cairo the foreign ministers of Egypt, Turkey and Iran were to meet to discuss developments in Syria on the political and humanitarian fronts, the Egyptian foreign ministry said.
Saudi Arabia is also a member of the group, but it was not immediately clear who would represent the kingdom at the talks.
Brahimi was to meet with the group, an Arab diplomat said.
On Tuesday the envoy was to visit the Altinozu refugee camp in Yurkey's Hatay province near the Syrian border, a Turkish official said.
Brahimi said Saturday the "crisis is dangerous and getting worse, and it is a threat to the Syrian people, the region and the world."
After he left Damascus on Sunday, a rebel commander said: "We are sure Brahimi will fail like the other envoys before him, but we do not want to be the reason of his failure."
Colonel Abdel Jabbar al-Okaidi, the Free Syrian Army commander in Aleppo, said Brahimi had insisted "the solution can only come from the Syrian people," but accused the international community of "giving political cover to the regime."
World powers, he said, were pushing the opposition to sit down for talks with the regime, but without pressuring the government to stop its repression.
Meanwhile Iranian foreign ministry spokesman Ramin Mehmanparast said Iran "does not have any military presence" in Syria, denying remarks by the head of the Revolutionary Guards General Mohammed Ali Jafari.