Syrian government forces recaptured territory in the contested city of Aleppo, reversing all gains rebels made two weeks into their counterattack.
The Syrian Observatory for Human Rights, a UK-based war monitor with sources on the ground, said on Saturday that the army and allies made several advances on the divided city's western edge, hampering the rebel offensive to break the siege on opposition-held districts.
The group said government forces regained control of Al-Assad and Minyan districts in the west of Aleppo.
State television said the army swept the suburban area for land mines.
"The 'epic battle for Aleppo' has failed," said the Syrian Observatory's chief Rami Abdurrahman, using the term the rebels had assigned to the offensive.
Zakaria Malahifji, head of the political office of the Fastaqim rebel group fighting in Aleppo, confirmed the army's gains.
"Of course, when the regime takes control, it has a negative effect, but there is persistence" among the rebel factions, he said. "And hopefully there will be change in the coming days."
The city has been divided for years between the government-held west and rebel-controlled east.
UN: Eastern Aleppo residents at risk of mass starvation
Syrian forces launched a major Russian-backed assault on eastern Aleppo in September after besieging the area, which is home to about 250,000 people.
On October 28, rebels counterattacked in a bid to break the siege, targeting western districts of Aleppo, but their progress slowed after early successes.
Aleppo has become the most intense front in the war pitting President Bashar al-Assad - helped by Iranian militias and Russian air power - against rebel groups, some backed by Turkey, the United States, and Gulf monarchies.
Russia said its air force has been observing a moratorium on air strikes on rebel-held eastern Aleppo since October 18.
I live in Aleppo, under siege
Prior to that, the Syrian Observatory and emergency workers said heavy air strikes had killed at least 450 people, and hit hospitals and other civilian facilities.
An armada of Russian warships, meanwhile, is now in the eastern Mediterranean off the Syrian coast after being sent to reinforce Russia's military in the area.
The commander of Russia's flagship Admiral Kuznetsov aircraft carrier, Sergei Artamonov, said via videolink the ships "are now jointly carrying out tasks, manoeuvering to the west of the Syrian coast".