The Syrian army advanced within firing range of the opposition's sole supply route to Aleppo during heavy fighting Thursday (July 7th), despite the announcement of a ceasefire for the Eid al-Fitr holiday, AFP reported.

Islamist opposition group Jaish al-Islam said four of its fighters were killed trying to stop the army from cutting the Castello Road, the only route into opposition-held areas of Aleppo.

Opposition fire on the regime-held Sayf al-Dawla district of the city killed three people, the Syrian Observatory for Human Rights said.

The army announced Wednesday it was observing a 72-hour nationwide ceasefire for the Eid al-Fitr holiday. But fighting has continued on the ground, particularly in and around Aleppo.

Regime forces have been trying to sever the Castello Road for more than two years, and the Observatory said Thursday's advance brought them the closest so far to achieving that goal.

The regime's capture of a hill just a kilometre away allows its forces to fire on traffic moving along the road from the ground as well as from the air, the Observatory said.