Islamist rebels in Syria have retaken a town from President Bashar al-Assad's forces, activists said on Friday, in part of an offensive along a stretch of the main highway linking Damascus to the northern city of Aleppo.

The Syrian Observatory for Human Rights said rebels killed 18 soldiers and disabled two tanks in the fight for the northern town of Babolin. The rebel assault coincided with a two-week-old offensive further west in the coastal province of Latakia, a heartland of Assad's minority Alawite sect, where fighters seeking to overthrow him have seized a border crossing and several villages.

Assad's army, backed by local militia and Lebanese Hezbollah fighters, has made steady gains around Damascus and in the Lebanese border areas, but his forces remain stretched and rebels have sought to seize the initiative elsewhere.

After capturing Babolin, rebels were battling pro-Assad fighters along a nearby 20-mile (30-km) stretch of highway between the towns of Morek and Maarat al-Nuaman, the Observatory, which is based in Britain, said.

The fall of Babolin puts pressure on two military bases on the edge of Maarat al-Nuaman held by Assad's forces. Rebels had blockaded the bases for six months, trying to cut Assad's main road link between Damascus and Aleppo, before they were pushed back in April 2013.

More than 150,000 people have been killed in Syria's three-year-old civil war, the Observatory said this week. More than 2.6 million people have fled Syria as refugees and another 6 million have been internally displaced by the violence.