Heavy clashes between troops and rebels raged into a second day in Syria’s second city Aleppo on Saturday, activists said, while a tense calm reigned in Damascus after days of fierce fighting.

The fighting in Aleppo came a day after the United Nations Security Council voted unanimously to grant a “final” 30-day mandate extension to a troubled observer mission charged with overseeing a peace plan for Syria.

The Syrian Observatory for Human Rights said that in Aleppo “battles have been ongoing since Friday morning between regular forces and fighters from rebel units in the Salaheddin neighbourhood.”

The Local Coordination Committees — a grassroots activist network — reported “an exodus of residents of the neighbourhood because of fear of regime bombardment and an offensive” against Salaheddin.

The fighting is the worst yet in the northern commercial hub, which had been largely spared from the protests and violence that have accompanied the country’s 16-month uprising against President Bashar Al Assad.

On Friday, activists said regime forces had opened fire on demonstrators in the city, killing at least one person.

In Damascus, a day after regime troops launched a major counter-offensive to retake rebel-held areas, residents reported the city was largely calm.

But the Observatory said regime forces had bombarded the Al Kaddam and Assali neighbourhoods on the southern outskirts overnight, and residents reported fighting in the Al Hajar Al Aswad and Tadamon districts.

A resident of the Yarmuk Palestinian refugee camp, on the outskirts of the capital, said he had not left since Wednesday.

“It’s dangerous to leave the camp because there are snipers posted at the entrance and they shoot at any gathering.”

The Observatory also reported government forces were shelling several districts of the rebel city of Homs, including Khaldiyeh, and said fighting was ongoing in the eastern city of Deir Ezzor.

After the Tuesday announcement by rebels of the “battle for the liberation of Damascus,” regime forces have stepped up operations in the city, as well as elsewhere in the country.

The Observatory said Saturday that death toll in nationwide clashes on Friday stood at 233, including 153 civilians, 43 regime troops and 37 rebel fighters.

The Britain-based group reported that Thursday was the deadliest day of the uprising so far, with 302 people killed nationwide.

On Friday, state television trumpeted the news of the military’s Damascus offensive.

“Our brave army forces have completely cleansed the area of Midan in Damascus of the remaining mercenary terrorists and have re-established security,” it said, using the regime term for rebels.

Reporters were taken on a regime-organised trip of the neighbourhood, where they saw empty streets, shuttered shops and buildings pockmarked with bullet holes.

The army’s counter-offensive came after a Wednesday bombing claimed by the Free Syrian army killed four senior members of the regime, including national security chief General Hisham Ikhtiyar, who died of his wounds on Friday.

Defence minister General Daoud Rajha, Assad’s brother-in-law Assef Shawkat and General Hassan Turkmani, head of the regime’s crisis cell on the uprising, were all killed in the explosion.

A state funeral was held for the three in Damascus on Friday ahead of their burials in their native provinces, the official SANA news agency reported, adding that Vice President Faruq al-Shara had attended but not Assad himself.

Rebel fighters on Friday battled for control of Syrian border crossings with Iraq and Turkey, briefly gaining control of the Albu Kamal post on the frontier with Iraq, as well as three crossing with into Turkey.

But amid a strong counterattack by regime forces, it was unclear on Saturday whether rebel forces had been able to retain control of the crossings.

At the United Nations, Security Council permanent members Russia and China both voted in favour of a resolution extending the mandate of the UN Supervision Mission in Syria for a “final” 30 days, after blocking an earlier text.

The resolution say the council could consider a further extension if violence reduces sufficiently to allow the mission “to implement its mandate.”