Syrian government forces captured a village from rebels in the central province of Hama on Saturday as they pushed a ground operation backed by Russian air support.
In Aleppo province to the north, rebels battled to reverse an advance by the Islamic State group that brought the jihadists to within a few kilometres (miles) of Syria’s second city.
And Washington said it would resume talks with Russia over ways to avoid military accidents in Syria’s increasingly crowded airspace.
In Hama, regime forces seized Atshan village from opposition fighters including Islamists and Al-Qaeda affiliate Al-Nusra Front, state television and the Syrian Observatory for Human Rights said.
The Observatory, a Britain-based monitoring group, reported heavy fighting around the village as regime forces sought to push northwest and take a neighbouring hilltop.
With support from Russian air strikes, they appear to be targeting the town of Khan Sheikhun, just across the provincial border in Idlib and on a key highway that runs from Aleppo to Damascus.
The highway is cut by rebel forces in several locations to the north of Khan Sheikhun.
– Rebels battle IS in Aleppo –
Hama province has been a key target for the Russian strikes that began on September 30, along with parts of the neighbouring provinces of Latakia and Idlib.
The strikes appear intended to prevent any advance by the Army of Conquest rebel alliance, which includes Al-Nusra, that holds Idlib and has sought to push into Hama and Latakia.
In Moscow, Russia’s defence ministry said Saturday that its forces had hit 55 Islamic State targets in the past 24 hours.
But rebels and their backers say Hama, Idlib and Latakia have little or no IS presence and accuse Russia of targeting moderate and Islamist opposition fighters more than the jihadist group.
The Observatory also reported heavy fighting on Saturday between regime forces and rebels in northern Latakia province.
Russian warplanes struck both Latakia and Idlib provinces on Friday and Saturday, including a raid in Idlib that destroyed a base belonging to a rebel group that has received US weapons, it said.
In Aleppo province, Islamist rebels including the powerful Ahrar al-Sham group recaptured one of several villages seized by IS in a Friday advance, the Observatory said.
The monitor added that rebels were battling to take back a second village from the jihadist group, which is now within 10 kilometres (six miles) of Aleppo city.
The IS offensive has brought the jihadists closer than ever to Aleppo, threatening to further complicate the situation in Syria’s second city which has long been divided between government and rebel control.
The regime holds the west of the city, while the rebels hold the east.
Elsewhere in Aleppo province, the Observatory said a powerful blast ripped through an explosives factory and weapons deport in the IS-held town of Al-Bab.
The cause of the explosion was unclear though unidentified warplanes were seen overhead around the time of the blast.
The Russian air campaign in Syria has angered rebels and their backers, while complicating efforts of the US-led coalition that is also targeting IS in the country.
– US, Russia airspace talks –
On Friday, the Pentagon said it would resume talks with Moscow aimed at preventing military accidents in Syrian airspace, after it received a response to US proposals.
“Department leaders are reviewing the Russian response and talks are likely to take place as soon as this weekend,” defence department spokesman Peter Cook said.
Also Friday, Washington acknowledged it had decided to “pause” a controversial programme to train and equip Syrian rebels to fight IS.
The programme had been slow to get off the ground because of stringent vetting, and the two small units that have so far entered Syria have met with disaster.
The first was attacked by Al-Nusra, which kidnapped and killed several of its members, while the second surrendered some of its weapons to the Al-Qaeda affiliate to ensure safe passage.