Russian news reports say the Syrian military is preparing a major operation with the Russian air force to regain control of the embattled northern city of Aleppo.
The Interfax news agency on Sunday quoted Syrian Prime Minister Wael al-Haiqi as saying the military push is aimed at freeing the city and blocking "all illegal armed groups which have not joined or broken the [February] cease-fire."
Haiqi also is quoted as saying that regaining control of the city from rebels would allow government forces to advance 300 kilometers to the east, toward the Islamic State stronghold of Deir Ezzor.
Fresh from recapturing the ancient city of Palmyra two weeks ago, forces loyal to Syrian President Bashar al-Assad have taken aim at the Deir Ezzor area, where IS militants control territory extending from their de facto capital, Raqqa, to the Turkish border and southward to Iraq.
Aleppo -- Syria's one-time economic capital, parts of which now lie in ruins -- has been divided into occupation zones since 2012, with rebel groups in some areas while other locales are still under government control.
Also Sunday, the London-based Syrian Observatory for Human Rights said at least 35 people were killed in overnight fighting on several fronts south of Aleppo. In a statement, the monitoring group said the dead included 19 members of the Islamist rebel group al-Nusra Front and 16 pro-Damascus fighters.
The United Nations says at least 250,000 people have been killed since the Syrian conflict erupted in March 2011. Human rights officials say more than 4 million others have been displaced by the fighting.
In a separate development, the United Nations World Food Program said Sunday it has delivered 20 metric tons of emergency food supplies in high altitude airdrops to 200,000 people trapped by fighting in and around Deir Ezzor since March 2014.
The agency said similar drops in February met with only partial success, with some supplies missing the drop zone and others damaged or destroyed when parachutes failed. It said more aerial drops are scheduled in the coming days to bring food and other humanitarian needs to the besieged city of more than 200,000 residents.