At least four people, including a woman and her child, have been killed in air raids on Syria's last major rebel stronghold in the northwest province of Idlib, opposition activists and a monitor have said.
The opposition's Syrian Civil Defence rescue group, also known as White Helmets, said the latest air strikes and artillery shelling targeted the village of in Bsakla and nearby places on Monday.
Three people died in Bsakla and the fourth, a man, in another village close by, Maaret Harmeh, the group said.
The Britain-based Syrian Observatory for Human Rights confirmed on Monday that a woman and her child were among three people killed in attacks on Bsakla village.
Al Jazeera was unable to independently confirm the death toll from Monday's air attacks.
The raids came as Syrian forces, backed by Russian warplanes, continued to make advances into Idlib province, which borders Turkey.
The Syrian troops on the offensive have recently captured rebel-held areas in the adjoining Hama province, as well as the town of Khan Sheikhoun in Idlib. From the town, they are now pushing north, towards the town of Maaret al Numan.
State news agency SANA said troops are pounding fighter positions in the town and several nearby villages. It said fighters fired rockets at government-held villages, inflicting casualties among the civilian population.
Maaret al Numan, like Khan Sheikhoun, sits on the M5 highway linking Damascus with the northern city of Aleppo. The Syrian government has been battling to take control of the strategic highway, a move that would allow it to connect cities under its control and boost trade.
Turkish tower attacked
Turkey has been a vocal opponent of Syrian President Bashar al-Assad and backs some of the rebels in northwest Syria, while it has also deployed forces in the Idlib region under agreements with Moscow.
Ankara last year struck a deal with Moscow to protect the Idlib province from a potential government offensive and agreed to disarm the rebels in the city, considered "terrorists" by Russia.
Also in line with the agreement, Turkish observation posts were established around the province to prevent hostilities.
Last Thursday, Turkish media, quoting officials, said that one of the country' observation towers in Idlib was surrounded and attacked by Syrian forces, without any casualties. Also last week, Ankara said that a Turkish military convoy was targeted.
Erdogan told Putin over the phone on Friday that attacks by the Syrian army in the northwest were causing a humanitarian crisis and threatening Turkey's national security, the Turkish presidency said.
The Kremlin said on Monday that Putin understood Erdogan's concerns, but that he was equally concerned about attacks by fighters in Syria that needed to be stamped out.
"Putin has repeatedly said he understands the concerns of our Turkish colleagues ... but at the same time, the president remains ... concerned about the activisation of action by terrorist elements from Idlib that cannot be [left] without being stamped out and destroyed," Kremlin spokesman Dmitry Peskov told reporters on a conference call.
Some 400,000 people have been displaced since the Idlib offensive began.