Syrian opposition forces backed by US airstrikes Wednesday lifted a siege on the frontline town of Marea, in northern Aleppo province, pushing back Islamic State fighters, a monitoring group said.
Marea is a key part of the last rebel-held enclave in Aleppo, a shrinking piece of territory near the border with Turkey.
"The siege has been lifted on Marea," Rami Abdel Rahman, head of the Britain-based Syrian Observatory for Human Rights, told dpa.
In May, Islamic State attacked Marea, a main town in the southern part of the enclave, cutting it off from the lifeline of A'zaz on the Turkish border. Some 160,000 people are trapped in the enclave, with Turkey having shut its borders.
The north of Aleppo was cut off from the south in February by government forces, backed by Russian air power.
The rebel push back of Islamic State comes amid a wider offensive against the extremists being led by the Kurdish dominated Democratic Forces of Syria (DSF) further to the east, in the so-called Minbij pocket. Minbij city is just 20 kilometres from the Turkish border.
Minbij is the last piece of territory Islamic State holds on the Turkish border, with Kurdish officials charging the group still has supply lines running over the frontier. The US also says the goal of the operation is to limit foreign fighter flows to Islamic State.
The offensive inside the pocket is being led by Arab brigades within the DSF, according to US officials. The US has launched more than 105 strikes in support of the battle.
Turkey itself has been wary of the offensive against Islamic State, as it is concerned about advances by Kurdish forces in the People's Protection Units (YPG), which has links to Kurdish fighters from the Kurdistan Workers' Party (PKK) in south-eastern Turkish provinces.
Turkey's Foreign Minister Mevlut Cavusoglu said he was given promises by the US that Kurdish forces would not remain in Minbij after Islamic State was ousted. Washington hasn't confirmed Cavusoglu's claim.
Meanwhile, in Aleppo city, the Syrian government stepped up on assault on rebel positions in the eastern sections, dropping barrel bombs from helicopters, according to activists. The city is split, but the rebel-held section is coming under increasing pressure.
The Syria Campaign, a pro-opposition advocacy group, said in a tweet: "Aleppo has run out of coffins and body bags. And the bombs keep falling."
Activist Mahmoud al Shahabi, who lives in Aleppo, said cemeteries are full and people are using "what remains of the public garden and children playgrounds to bury their loved ones."
The defence ministers of Iran, Russia and Syria are scheduled to meet on Thursday in Tehran to discuss the battle against Islamic State, according to Iranian media reports.