Beirut: Syrian regime forces have battled jihadists who cut a key supply route west of ancient Palmyra, after new bombardments hit Aleppo city where a ceasefire was due to expire at midnight.
The latest fighting comes as world powers prepare to meet in Vienna next week to try to revive peace talks aimed at ending a five-year conflict that has killed more than 270,000 people.
The Syrian Observatory for Human Rights, a Britain-based monitor, said the Islamic State (IS) group on Tuesday cut the main road from Homs city to Palmyra just weeks after the army recaptured the city, a UNESCO world heritage site.
A military source told the SANA official news agency yesterday that the Syrian air force had carried out strikes against IS around the main facility in the Shaer gas field, northwest of Palmyra.
A security source told AFP: "Military operations are ongoing in the Shaer gas field," which is one of the biggest in the central province of Homs.
Both sides have been battling each other in the desert around Palmyra since IS was ousted from the city in late March.
The jihadist group last week seized the Shaer gas field from the regime.
President Bashar al-Assad's troops retook Palmyra with support from Russian air strikes on March 27 -- an achievement his regime celebrated with concerts in its ancient amphitheatre last week.
But IS now surrounds Palmyra from all directions except the southwest, Observatory chief Rami Abdel Rahman said, adding that IS was within 10 kilometres of the city.
In Deir Ezzor province further east, at least seven civilians were killed, including a child, in regime air strikes on an area held by IS.
They died in "regime air strikes on the Shuhail district in the east of Deir Ezzor province targeting a health facility and other areas in the district", the Observatory said.
The Russian defence ministry's coordination centre in Syria meanwhile said there had been five breaches of a ceasefire in Aleppo over last 24 hours, killing eight civilians.
The local truce - brokered by Russia and the United States after a spike in violence in the city last month - was set to expire at midnight yesterday.