BEIRUT (AP) -- Syrian insurgent groups launched a fresh offensive Saturday seeking to break a government siege on rebel-held neighborhoods in the northern city of Aleppo, triggering intense clashes and airstrikes on the southern edge of the metropolis, the militants and state media said.
An unnamed military official told state news agency SANA that "large numbers" of militants attacked the military college in Aleppo, adding that government forces are defending the sprawling base. SANA said the militant offensive was preceded by a number of car bombs that struck the area.
The government completely closed the main road into the rebel-held areas of Aleppo on July 17, effectively besieging the neighborhoods. The United Nations estimates that between 250,000 and 300,000 residents have been trapped in the besieged, eastern part of Aleppo since mid-July.
The U.N. and numerous relief organizations have warned of a looming humanitarian catastrophe as conditions there deteriorate.
The powerful ultraconservative Ahrar al-Sham group, which is taking part in the offensive along with several other factions, posted a video that showed what it said were its fighters inside the college known as the Artillery Academy. An Ahrar al-Sham fighter in the video claimed that militants are in full control of the college showing destroyed tanks and artillery pieces captured by the gunmen. Ahrar al-Sham's coalition includes the Levant Conquest Front, al-Qaida's branch in Syria which recently renamed itself and announced its separation from the global al-Qaida organization.
"It is only a matter of hours before we break the siege imposed on our brothers in Aleppo," an Ahrar al-Sham fighter said in the video as gunfire could be heard in the background.
The video appeared genuine and corresponded to other Associated Press reporting of the events.
A State TV reporter in the area said the fighting was intense inside the college. The Lebanon-based Pan Arab TV station Al-Mayadeen, that has reporters on the government side of the city, reported that Syrian government reinforcements are being sent into conflict zone.
The military college is located about 1.6 kilometers (1 mile) from the besieged opposition areas.
The Britain-based Syrian Observatory for Human Rights said insurgents are now in control of large parts of the college.
Earlier Saturday, activists said predominantly Kurdish fighters are now in control of most of a stronghold of the Islamic State group in northern Syria after a push under the cover of airstrikes by the U.S.-led coalition.
The Observatory said Syria Democratic Forces are in control of most of the town of Manbij amid fighting in northern neighborhoods and the town's center.
Mustafa Bali, a Syria-based Kurdish activist, said that IS still holds some areas in Manbij, including the major northwestern neighborhood of Sarab.
Bali said "it's a matter of time" before SDF fighters capture the town.
If Manbij is captured by SDF, it will be the biggest strategic defeat for IS in Syria since July 2015, when the extremists lost the border town of Tal Abyad.