Syrian regime forces on Friday battled Islamic State group jihadists near Aleppo city, even as they clashed with local Al-Qaeda affiliate the Al-Nusra Front and allied rebels nearby, a monitoring group said.
The upsurge in fighting, which the United States says is straining a fragile truce, came as a new round of peace talks got under way in Geneva.
"Fierce fighting raged between regime troops and loyalist militia against IS... to the east of Khanasser" southeast of Aleppo city, the Syrian Observatory for Human Rights said.
The army is trying to recapture several areas seized by IS on Thursday near Khanasser, the Britain-based monitor said.
Meanwhile, troops and militia loyal to President Bashar al-Assad's regime battled Syria's Al-Qaeda affiliate Al-Nusra Front and allied rebels on a northern front in the battered province, the group said.
At least 14 troops and pro-regime militiamen as well as 20 rebels and Al-Nusra jihadists have been killed in the past 24 hours around the flash-point area of Handarat north of Aleppo city, it said.
The latest violence came a day after a senior official in Washington told AFP that the United States was "very concerned" about reports of a Russian-backed Syrian government offensive near Aleppo.
Even though the fight against IS and Al-Nusra is excluded from the truce, violence around Aleppo has sparked concerns that the ceasefire may not last, partly because other rebel groups are involved in the battles there too.
"Aleppo is the key to war and peace in Syria," Observatory director Rami Abdel Rahman told AFP.
"Every side in the war has a stake in Aleppo."
Syria's conflict began in 2011 as a peaceful revolt, with protests across the country that spread in 2012 to Aleppo province, which borders Turkey. A report from the Syrian Center for Policy Research said that a staggering 470,000 Syrians had died as a result of the war, almost twice the 250,000 counted a year and a half ago by the United Nations, until it stopped counting because of a lack of confidence in the data.
With inputs from AFP