Syrian activists say government aircraft have dropped barrel bombs on the northern city of Aleppo, killing at least eleven people.

The Britain-based Syrian Observatory for Human Rights says the makeshift bombs were dropped on two rebel-held districts of Aleppo on Sunday afternoon. A child and a woman are among those who died, the Observatory said.

Sunday's attacks are part of a weeks-long campaign by Syrian President Bashar Assad's forces to wrest control of Aleppo, parts of which were seized by rebels in mid-2012.

Barrel bombs are containers that have been packed with hundreds of kilograms (pounds) of explosives. They are loaded onto Syrian military helicopters and pushed out of the rear door.

Aid operations to resume in Homs

Meanwhile, aid workers are expected to return to the besieged city of Homs on Sunday, a government official said, a day after trucks carrying food and medical supplies came under fire.

The attack wounded an aid worker and jeopardized a rare cease-fire in the nearly 3-year-old conflict hours before the resumption of peace talks in Geneva.

Khaled Erksoussi, the head of operations at the Syrian Red Crescent told The Associated Press that the agency will try to evacuate more civilians from rebel-held areas in Homs in line with a UN-brokered agreement on a three-day truce to enable some people to leave and allow entry of food shipments.

Syrian forces loyal to Assad have prevented the entry of food and medical aid into rebel-held parts of Homs for over a year, badly affecting hundreds of civilians holed up in the areas.

Erksoussi said 83 children, women and elderly people on wheelchairs have been evacuated since Friday when the truce went into effect. It was broken a day later, leaving an aid worker wounded and two trucks damaged, Erksoussi said in a phone interview from Damascus.

He said aid workers did manage to deliver 250 food parcels and 290 hygiene kits as well medicine to the central, rebel-held neighborhood of Hamidiyeh Saturday, but no one was evacuated from the besieged area because of the attack.

"We barely got our staff out alive," Erksoussi said.

It was not clear who fired at the convoy. Syrian state TV said members of the Red Crescent were wounded by rebel fire in the area, but gave no further details.

Opposition activists blamed the government-allied militia for the attacks.

Homs city was one of the first areas to rise up against Assad in 2011 and has been particularly hard hit by the war. Over the past year, the government has regained control over much of the city, except for a few neighborhoods in the historic center.

The Syrian uprising began with largely peaceful protests but gradually evolved into a civil war with sectarian overtones pitting predominant Sunni Muslim rebels against Assad's government that is dominated by Alawites, an offshoot group of Shiite Islam. More than 130,000 people have been killed, according to activists. Millions have been forced out of their homes, seeking shelter in neighboring countries or in safer parts of their homeland.

There have been few cease-fires during the conflict. Over the past year, several temporary truces were negotiated to allow for the evacuation of civilians and the delivery of food parcels in and around Damascus.

U.N. mediator Lakhdar Brahimi had pushed for aid for the estimated 2,500 civilians trapped in the ancient, rebel-held quarters known as Old Homs as a confidence-building measure during the first face-to-face meetings of government officials and opposition figures in Geneva last month.

There was no tangible progress, as the Syrian government accused the opposition of capitalizing on human suffering in Homs to score points with the international community.

A second round of talks is set to start on Monday.