Islamic State (IS) militants have launched their biggest attack in months on government-held areas of the Syrian city of Deir al-Zor on January 14, a monitoring group reported.

At least six large explosions shook the city as militants clashed with government forces, the British-based Syrian Observatory for Human Rights said.

Syrian state television reported that IS shelling killed three people and wounded nine in government-held districts.

Syrian government warplanes hit back against the Islamic State positions.

Islamic State, which controls most of Deir al-Zor province, has also held the provincial capital under siege since 2014.

Government troops have survived the siege thanks to air-dropped humanitarian assistance and weapons and ammunition flown into a nearby military airport controlled by the government forces.

Some 200,000 people live in the encircled zone, lacking food and medicine. The Syrian government and its ally Russia have made regular aid drops.

Syrian opposition activists have also reported fighting near the military airport.

Deir al-Zor province is strategically important to IS militants because it links IS’s de facto capital in the Syrian city of Raqqa with territory they control in Iraq

Based on reporting by Reuters and AP