Syrian government and Russian jets have been heavily bombarding towns in Idlib province, as fighting rages between pro-Assad forces and opposition fighters in several other provinces, Al Jazeera has learned.

At least 44 people, including six children, were killed in 24 hours due to Russian and Syrian airstrikes across the country, the Syrian Network for Human Rights (SNHR) reported on Saturday.

Abdel Rahman of the Syrian Civil Defense organization told Al Jazeera air strikes on Friday targeted the town of Killi in Idlib and left at least five people killed, including three children.

"The Syrian Civil Defense team were doing their jobs and rescuing people. The air strikes that targeted those areas were a second round of air strikes. After our volunteers gathered to help save those injured and evacuate the area they were attacked for a second and third time.

"This is not the first time we have lost volunteers in the same way," Abdel Rahman said.

"Last Tuesday, Russian air strike struck Sarmin town in Idlib, while civil defense volunteers tried to evacuate a square following an earlier air strike. That second strike left at least 12 civilians, and one civil defense volunteer killed. " He added

Elsewhere, battles have intensified between government forces, Islamic State of Iraq and the Levant (ISIL) group and opposition fighters in Hama, Aleppo and Idlib in the past 24 hours.

The UK-based Syrian Observatory for Human Rights said at least 90 fighters were killed in those battles since Friday. The death toll includes 21 government forces, 28 ISIL fighters and 16 opposition fighters.

Hadi al-Abdullah, a media activist in Idlib, told Al Jazeera that the air strikes in Idlib and Hama have not stopped in the past few days.

"The air strikes do not stop during the day nor during the night, they are endless. Russian air strikes have intensified on Idlib, Hama and Aleppo in the past few days — the air strikes are targeting civilian areas. We lost our colleague, Wassim Al Adel, in the attack on Friday.

"I think the reason Russian air strikes are targeting civilian areas is because they think that Syrians might eventually take their side.

"Syrian rebels captured two villages in Hama province and have destroyed so many tanks. In reaction to this, Russian airstrikes have intensified," al-Abdullah said.

"The situation in Idlib is very difficult and the government is advancing."

Russia says its strikes are against ISIL and other "terrorists", but rebels and the US, which is conducting its own campaign against ISIL and some rebel factions, say Moscow has focused more on opposition forces than ISIL.

The observatory said that at least 370 people, including 127 civilians and 36 children, have been killed by the Russia air strikes since September 30.