Al Qaeda-linked rebels battled government forces in deadly clashes in the Syrian city of Idlib on Monday.

At least 39 people were killed in the fighting, including four civilians, the London-based Syrian Observatory for Human Rights said.

Regime forces have recaptured two key government buildings -- the governor's mansion and police headquarters -- after rebels from several groups including the al Qaeda-linked al-Nusra front stormed them, the observatory said.

Fighting between government forces and Islamist rebels is still occurring on the outskirts of the city, the observatory said.

Flashpoint Partners Intelligence, which monitors jihadist communications, said Monday that al-Nusra claims to have captured the town of Tall Mastumah, blocking the Syrian government's supply route to Idlib. Al-Nusra also claims to have captured 12 Syrian soldiers, according to Flashpoint.

Idlib, in northwest Syria not far from the Turkish border, is roughly 66 kilometers (41 miles) from Aleppo, Syria's largest city.

(CNN)