Deadly clashes rocked a district of Damascus on Monday as international efforts picked up pace to initiate a daily humanitarian truce and for monitors to be deployed across violence-swept Syria.
President Bashar al-Assad's security forces, meanwhile, launched attacks in several regions, opposition activists said.
The pre-dawn fighting in a heavily guarded area of Damascus, the capital's fiercest since a revolt against Assad's regime erupted a year ago, came as residents still reeled from deadly weekend bombings.
At least three rebels and a member of the security forces were killed in the upscale western neighbourhood of Mazzeh, state television and monitors reported.
"Three terrorists were killed and a fourth was arrested in the fighting between security forces and an armed terrorist gang sheltered in a house of a residential district," the television channel said.
Rami Abdel Rahman, head of the Syrian Observatory for Human Rights, said four rebels were killed. The fighters fired a rocket-propelled grenade at the home of a top army officer as they brought the conflict to the capital, he said.
Mourtada Rasheed, an activist in Damascus, said blasts and heavy shooting could be heard in Mazzeh and two other districts, Qaboon and Arbeen.
A Qaboon resident who did not wish to be identified said "we woke up at 3:00 am (0100 GMT) to the sound of heavy machinegun fire and rocket-propelled grenades."
In Mazzeh, which is overlooked by Assad's clifftop presidential palace and home to several embassies, terrified locals were woken by the rattle of gunfire. "We were very scared," one told AFP.
On the humanitarian front, the international Red Cross said its chief had received "positive indications of support" from Moscow on his proposal for a daily two-hour truce for aid workers to deliver relief.
"The ICRC received positive indications of support for our initiative of a daily halt in fighting in all the regions affected by the violence," said an International Committee of the Red Cross spokesman in Geneva.
An ICRC spokeswoman in Moscow said the meeting was a part of Kellenberger's broader efforts to prompt world powers to secure commitments from the regime and rebels to lay down their arms for a few hours each day.
"The ICRC hopes to see concrete results of such meetings on the ground in the coming days and weeks," Victoria Zotikova told AFP.
A mission sent by UN-Arab League special envoy Kofi Annan arrived in Damascus for talks on a monitoring operation to end the conflict that monitors say has cost more than 9,100 lives since last March.
"There are five people with expertise in political, peacekeeping and mediation," Annan spokesman Ahmad Fawzi told AFP, declining to disclose their precise plans or whereabouts.
"They will be staying for as long as they are making progress on reaching agreement on practical steps to implement Mr Annan's proposals," he added.
France on Monday proposed a UN Security Council statement giving strong backing to Annan's efforts. "The aim now is to find common ground and send a strong message to the Damascus regime," a diplomat in New York said.
Separately, technical experts from the UN and Organisation of Islamic Cooperation are taking part in a Syrian government-led mission to assess the impact of the deadly crackdown.
The seven-to-10-day mission to 15 cities, on the first such assignment in Syria since the violence started, was launched in the flashpoint province of Homs on Sunday.
Monday's clashes in the capital came after twin car bombs ripped through two neighbourhoods of Damascus on Saturday, killing 27 people, according to the interior ministry.
An Observatory statement said fresh fighting broke out several hours later between rebels and security forces in the Qaboon and Barzeh areas of Damascus.
Troops backed by dozens of tanks raided districts of Deir Ezzor city in eastern Syria on Monday, the Observatory said, a day after at least 25 army deserters were killed in seizing its Hamidiyeh district.
Five soldiers, including two officers, were also killed, it said.
Security forces killed at least 10 civilians on Monday, including a young girl, in Idlib, Homs and the southern province of Daraa, while a captain who deserted was killed in the central town of Rastan, the Observatory said.
Source: AFP Global Edition