Damascus (AFP) - Syrian troops and allied militia pushed rebel fighters back on Wednesday from a hilltop overlooking a strategic highway in President Bashar al-Assad's coastal heartland, state media said.

Citing a military source, state news agency SANA said army units and pro-government militia "took full control of the strategic Jabal Nuba after killing a number of terrorists".

Rami Abdel Rahman, head of the Syrian Observatory for Human Rights monitor, told AFP the hill overlooks the main rebel supply line between Latakia -- a bastion of Assad support -- and second city Aleppo.

The government intensified its offensive to retake Jabal Nuba in recent weeks and Russian warplanes had carried out raids in the area in support of the army.

On Wednesday, army units fought through dense brush and mountainous terrain, and were "combing through the area to clear any booby-trapped devices", the military source said.

He said the army would continue to "tighten the noose" around rebel positions, including in the village of Salma which has been in anti-government hands since 2012 and has been the target of heavy Russian bombardment.

Groups including Al-Qaeda affiliate Al-Nusra Front have taken up positions around the village, according to the Observatory.

The Britain-based monitor confirmed that Syrian army units were backed by Lebanese Shiite group Hezbollah in the offensive.

"The clashes also came with dozens of air strikes, rocket fire, and heavy shelling on the Jabal Akrad and Jabal Turkman regions," the Observatory said.

Fierce fighting has rocked those areas in recent months as the regime seeks to recapture opposition-held territory in Latakia.

According to Syria analyst Fabrice Balanche, Jabal Nuba is between 500 and 800 metres (1,650 and 2,640 feet) high.

"Its capture allows the regime to control the access to Salma from the west, as the army already controls the access point from the east," Balanche told AFP.

"Taking Jabal Nuba is ringing in the upcoming fall of Salma, which will be celebrated as a major victory."

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On November 24, anti-government factions destroyed a Russian helicopter after firing on it and forcing it to make an emergency landing near Jabal Nuba.

Russia began its air war in Syria in September and has said it is fighting the Islamic State group and other "terrorist" organisations.

Tensions have skyrocketed in recent weeks since Turkey shot down a Russian aircraft over Latakia and rebels killed one of the two crew as he parachuted to earth after ejecting.