DAMASCUS - The Syrian air force on Monday carried out as many as 40 airstrikes against rebel positions in central and northern Syria, a monitoring group reported.

The air force conducted 15 airstrikes on rebel positions in the northern province of Idlib and at least 23 others on rebel targets in the central province of Hama, said the London-based Syrian Observatory for Human Rights, which relies on a network of activists on the ground.

Government troops have recently made progress against rebels in the northern countryside of Hama, stripping al-Qaida-affiliated militants of key parts in the strategic area.

The Observatory didn't elaborate on the losses and possible casualties resulted from the government airstrikes.

Also on Monday, the Islamic State (IS) militant group detonated a booby-trapped vehicle on a road connecting the northern Kurdish city of Kobane with the Turkish border, said the Observatory.

In Kobane, also known as Ayn al-Arab, intense clashes continued Monday between IS militants and Kurdish fighters of the People Protection Units (YPG), the Observatory said, adding that four IS fighters were killed Monday and that their bodies are with YPG fighters.

The clashes in Kobane started over three weeks ago when IS fighters unleashed their offensive to capture the strategically town on the Syrian-Turkish border.

Government troops have ramped up their assaults on rebel fighters in central and southern Syria recently in what observers believe is a new tactic aimed at taking advantage of U.S.-led airstrikes to achieve more progress against the rebels.