Rebels say they have breached the siege imposed by the Syrian government on opposition neighborhoods in the northern city of Aleppo, in a major military breakthrough after intense fighting.

The Syrian government seized the only route into rebel-held areas in northern Aleppo last month, prompting a rebel counteroffensive from the city's south. The U.N. said 300,000 people were trapped, making Aleppo one of the largest besieged areas in Syria.

A broad coalition of rebel groups posted videos Sunday of fighters roaming the Ramouseh district, where the siege was breached following overnight clashes. The district houses a number of military colleges.

The war media arm of Lebanon's Hezbollah, the group fighting alongside the Syrian government, conceded the rebels' advance, adding that airstrikes leveled one of the military colleges after forces withdrew.