State media say rebels forced out of areas near Aleppo airport as the UN chooses a new UN-Arab League envoy to Syria.
Jets and helicopters have continued to strike the northern suburbs of Aleppo as Syrian forces reportedly battle rebels near the airport in the war-battered city.
A constant flow of casualties were rushed to a local hospital that had been allegedly targeted on Friday.
Fierce fighting was also reported in Damascus, a day after the United Nations called time on its observer mission.
Syria's official SANA news agency said that "armed terrorist groups" - the regime's phrase for rebels - had been pushed out from areas on both sides of the airport, which is located about 15km southeast of Aleppo's historical centre.
The report on Friday was the first official acknowledgement that fighting has reached the doorstep of the strategic site in the country's largest city.
It did not make it clear whether the fighting was closer to the international airport or the adjacent military airfield, a hub for air strike missions on rebel sites in the north.
Rebel footholds in Aleppo have been the target of weeks of shelling and air attacks as part of wider offensives by President Bashar al-Assad's forces.
In Damascus, the capital, activists said the army clashed with rebels near the main military airport and shelled southern parts of the city.
The latest reports of violence came as UN officials in Syria were starting to close down their military observer mission after failed international attempts to negotiate a ceasefire.
'The path of war'
Lakhdar Brahimi, a veteran Algerian diplomat, will take over from Kofi Annan as
the UN-Arab League Joint Special Representative in the Syria conflict, the United Nations said Friday.
UN leader Ban Ki-moon appealed for "strong, clear and unified" international support behind Brahimi as he announced the appointment in a statement.
But the council remains deeply divided on how to proceed with Syria.
The UN Security Council decided to end the mission this coming Sunday, but a small new liaison office is planned to support any future peace efforts.
Edmond Mulet, the UN assistant secretary-general for peacekeeping, said both sides had "chosen the path of war".
Earlier this year, the UN authorised sending up to 300 unarmed military observers to Syria to monitor a ceasefire that UN-Arab League envoy Kofi Annan negotiated with Assad.
But hostilities have only worsened since then, and the UN mission suspended its patrols on June 15, leaving the observers largely confined to their hotels.
Meanwhile, former Syrian prime minister Riad Hijab, who defected earlier this month, was in Qatar for talks about how to unify opposition efforts to topple Assad, his spokesman said on Friday.
Hijab, who announced his defection on August 6 becoming the most senior serving official to quit Assad's administration,
arrived on Thursday for a three-day visit.
Russia on Friday rejected a proposal to set up no-fly zones to help civilians flee fighting in Syria's border areas after the
United States said it was ready to consider the move.
"You have to solve citizen security issues using methods put in practice by international humanitarian law," Foreign Minister Sergei Lavrov told Sky News Arabia in an interview to be aired in full on Saturday and released to Russian
"But if you try to create no-fly zones and safety zones for military purposes by citing an international crisis - this is unacceptable," he said.
Russia and China have vetoed three Western-backed Security Council resolutions criticising Damascus and threatening sanctions.
Civilians continue to be targeted, and on Thursday activists reported that Syrian forces shelled a group of people queueing outside a bakery in the Qadi Askar district of eastern Aleppo.
The news followed accusations by rights groups that the Syrian regime had committed another atrocity on Wednesday when around 40 people, including women and children, were killed in an air strike on civilians in the rebel bastion of Azaz, north of Aleppo.
On Friday, a Turkish diplomat said that more than 2,000 Syrians, including one defecting general, fled to Turkey after the violence in Aleppo.
The latest group of 2,204 people brought the number of Syrian refugees in Turkey to more than 62,000, the diplomat told AFP news agency on condition of anonymity.