Syrian government troops, backed by Russian airstrikes, have recaptured two strategic towns from Islamist rebels in the central province of Hama.
"The regime managed to take control of Tel Asked which is located at the outskirts of Hama and near the southern outskirts of the province of Idlib," the head of the Britain-based Syrian Observatory for Human Rights, Rami Abdel Rahman told dpa.
Earlier regime troops overran the village of Atshan in north-eastern Hama, the watchdog said.
Abdel Rahman said the area is of strategic importance to government forces because it brings them closer to the town of Khan Sheikoun, a stronghold of al-Qaida affiliate al-Nusra Front, in Idlib.
Al-Nusra seized Khan Sheikoun in 2014, giving the militants control of a stretch of the M5 highway connecting Damascus with central and northern Syria.
Abdel Rahman also said that a Russian jet was "hit by rebel fire but not downed" over the Mansoura area in Sahel al-Ghab in the province of Hama, where heavy fighting was taking place between rebels and the Syrian army.
On Wednesday (local time), the Syrian army, backed by fighters from the allied Lebanese Hezbollah movement and Russian fighter jets, started a major offensive against rebels on the outskirts of the provincial capital, also called Hama.
Syrian television said government troops advanced near Hama, killing more than 125 "terrorists," a term used by state media to describe opposition rebels fighting to oust President Bashar al-Assad.
The Russian Air Force flew 64 missions, hitting 55 targets in the past 24 hours, the Defence Ministry said on Saturday.
The focus, it said, was command and communication centres, ammunition depots and training camps of Islamic State militants in Hama, the neighbouring provinces of al-Raqqa and Aleppa, and Damascus.
But the observatory said the airstrikes also hit areas under the control of government opponents who are also fighting Islamic State.
Islamist rebels on Saturday recaptured a village in Aleppo from Islamic State, a day after the extremist militia overran it, the observatory said.
The Islamist rebels, including the coalition of Ahrar al-Sham, retook the village of Tal Soussin and are battling Islamic State over the control of Tal Qrah, a second village in the northern part of Aleppo, the Britain-based monitoring group said.
Islamic State's push in Aleppo threatens a main road used by rival jihadist rebels for access to the Turkish border.