Clashes between pro-government forces and extremist groups that control Syria's north-west killed at least 45 combatants on Tuesday (June 18th), AFP reported.
The fighting flared on the edge of Hama province when extremist alliance Tahrir al-Sham launched a dawn attack on regime positions, the Syrian Observatory for Human Rights said.
At least 31 extremist elements and 14 pro-government forces died in ensuing clashes, the monitor said.
"Regime forces foiled the attack," Observatory head Rami Abdul Rahman told AFP.
State news agency SANA also said the offensive had been thwarted.
Hama's northern countryside lies on the edge of a jihadist-controlled region including most of Idlib province.
The frontline had been relatively calm since clashes on Saturday killed more than 35 combatants, including extremists and regime forces, Abdul Rahman said.
Regime airstrikes on northern Hama and neighbouring Idlib had also paused for more than 24 hours, before resuming Tuesday following the latest bout of fighting, according to the monitor.
The bombardment killed one civilian in southern Idlib, it said.
The latest battles come after rocket fire by Tahrir al-Sham and allied groups killed more than 12 civilians in a regime-held village in Aleppo province late Sunday.