Regime forces have rained shells on rebel bastions in and around Damascus and extra troops are headed north to join the battle for the commercial capital Aleppo, as the conflict roiling Syria intensified.
The fresh offensive came hours after UN chief Ban Ki-moon urged Damascus to show compassion to its people and Syrian Foreign Minister Walid Muallem said a political solution was still possible if the West and Gulf states halted support for the rebels.
The Syrian Observatory for Human Rights said on Tuesday at least five civilians died when Douma, in the capital's northeast, was rocked by shelling following a deadly raid by rebels overnight on an army post there in which six soldiers were killed.
An amateur video posted by activists reported an exodus of residents of Douma and showed several vehicles with women inside driving off in the dark of night.
Troops loyal to President Bashar al-Assad also blasted a string of rebel strongholds in towns and suburbs outside the capital, including Babila, Hosh al-Arab, Saqba, Zabadani and Jubar, the Britain-based Observatory said.
South of the capital, security forces raided the Tadamun district and fierce clashes broke in the nearby Yarmuk Palestinian camp, the watchdog said.
The Local Coordination Committees, an activist network, reported that more than 100 shells fell on Zabadani, once a resort destination known for its mild weather and scenic views just northwest of the capital but now devastated by the civil war ravaging Syria.
The official daily Al-Baath on Tuesday said the "end of security operations throughout Damascus province" was approaching.
Government forces "have destroyed many weapons caches and seized large quantities of ammunition and equipment... which indicates that the end of security operations throughout Damascus province is approaching," the newspaper said.
On July 18, rebels carried out a massive bombing on a security complex in Damascus, killing Assad's brother-in-law, the defence minister and a general.
Since then, regime forces have pushed the rebels to the outskirts of the capital but have lost control of several border crossings and are battling to fully retake Syria's second city of Aleppo, which has been the focal point of the conflict since mid-July.
Several districts of Aleppo were bombed on Tuesday, the Observatory said, a day after 22 civilians died in the violence ravaging the city.
Fighting flared in the Aleppo districts of Sakhur, Sheikh Khodr, Sheikh Faris and Arkoub, where one rebel was killed, and along Suleiman al-Halabi Street in the city centre, the Observatory said.
Pro-regime daily Al-Watan said on Tuesday that extra troops were being sent to Aleppo.
"New reinforcements have arrived to support the army... and the armed men (rebels) are now fatigued and have begun to flee to their villages and towns in the province of Aleppo and elsewhere," the paper said.
"This is a sign of the determination of the Syrian army to win the battle of Aleppo as soon as possible," it added.
The government warned in July that Aleppo should brace for the "mother of all battles" but has failed to dislodge opposition fighters from many districts.
In turn, the rebels announced last week that they had launched the final campaign to take the city, but that has stalled.
Fighting at the weekend rocked the centuries-old UNESCO-listed souk in the centre of Aleppo and sparked a fire which damaged hundreds of shops and dealt a severe economic blow to the city.
Violence also raged on Tuesday in the southern province of Daraa, the Observatory said, adding that nine rebels were killed in an explosion at dawn near the Jordanian border while another nine people, including a pregnant woman, were killed in shelling attacks and clashes between troops and rebels in a camp for displaced people.
And Turkish troops fired across the Syrian border, killing a member of a Kurdish militia and wounding two others in the first such fatal shooting at the Turkish frontier, said the Observatory.
On the political front, Ban said after a meeting with Syria's Muallem at UN headquarters in New York that it was time for Damascus to lower the scale of its offensive against the insurgency.
"He stressed that it was the Syrian people who were being killed every day and appealed to the government of Syria to show compassion to its own people," a spokesman said.
Muallem, meanwhile, told the UN General Assembly that France, Qatar, Saudi Arabia, Turkey and the United States "clearly induce and support terrorism in Syria with money, weapons and foreign fighters."
Assad was open to reforms if the violence stopped, the foreign minister said. "We still believe in a political solution as an essential way out of the crisis."
For this to happen, he said UN members should press for an end to the "arming, financing, harbouring and training of terrorist groups."
At least 30,000 people, including more than 2000 children, have died in the conflict since it erupted in March 2011, according to figures supplied by the Observatory.
The UN refugee agency said in Geneva on Tuesday the number of Syrian refugees in neighbouring countries has more than tripled since June to over 300,000, and by the end of the year that number will more than double again.