Backed by relentless Russian airstrikes, Syrian troops and allied militiamen on Wednesday pushed deeper into a major rebel stronghold in the northwestern province of Latakia, a day after seizing a key rebel-held town in the strategic region overlooking the coast, the government and opposition activists said.

The insurgents in the opposition-held area near the Turkish border were collapsing after the town of Salma fell to government loyalists late Tuesday. Salma's fall marked one of the most significant military victories by the Syrian military since Russia began airstrikes in the country last September to shore up President Bashar al-Assad's forces.

On Wednesday, government troops seized the villages of Mrouniyah and Marj Kawkah near Salma as they continued their advances in the region, aided by immense Russian firepower.

Salma, part of mountainous chains near the border with Turkey known as Jabal al-Akrad and Jabal al-Turkmen, has been under rebel control for the past three years.

'It was hell on earth'

The town, where members of Assad's Alawite minority sect once co-existed with majority Sunni Muslims, overlooks the largely Alawite coast and is about 12 kilometres away from the Turkish border. Turkey is a key supporter of insurgents in the area, which is mostly inhabited by Syrian Turkmen, an ethnic minority with close ties to Turkey.

"Whoever controls Salma gains control all those surrounding areas which it overlooks," said Zakariya Ahmad, an opposition activist in the nearby Idlib province.

A boy carries a baby in a site hit by what activists said were airstrikes carried out in January by the Russian air force in the town of Douma. Russian has been bombing Syria since September. (Bassam Khabieh/Reuters)

He said the town fell after 93 days of fighting and daily barrel bombs and airstrikes. He said activists in the region had reported 92 airstrikes believed to be Russian on Salma in the last 24 hours before it was fully seized by government troops.

"It was hell on earth," he said.

Salma's capture further improves Assad's position ahead of planned peace talks with the opposition in Geneva scheduled for January 25, and came as high-level U.S., Russian, UN and other diplomats met behind closed doors in Geneva on Wednesday to discuss efforts to those talks.

The recapture of Salma is the latest in a string of military achievements by the government recently, supported by Russian air power and Lebanon's Shiite militant Hezbollah group.

Fawaz Gerges, a Middle East expert at the London School of Economics, said Russia was trying to send a powerful message to Turkey following the downing of their plane in November in the area, showing that they can exact revenge.

"Salma is really a major breakthrough, not just for the Syrian army, for Russia as well," he said, adding that losing the town was a significant loss for the opposition.

"The rebels thought they could turn it into a spearhead to deal a mortal blow against the regime" into its Alawite heartland, he added.

Coastal area effectively under army control

Russia began conducting airstrikes in Syria on Sept. 30 against ISIS and "other terrorists," but much of the Russian airstrikes have targeted areas where ISIS has no presence.

Jabal al-Akrad, where Wednesday's fighting was focused, is also close to the rebel-held northwestern province of Idlib, which has frequently been targeted by Russian warplanes since Moscow launched its air campaign. It is controlled by a consortium of mainstream and extremist insurgent groups including the ultraconservative Ahrar al-Sham and the Nusra Front.

Latakia province includes key strongholds of Assad and the Alawite religious minority.

Sharif Shehadeh, a Syrian member of parliament, said the capture of Salma "effectively brings the entire coastal area under Syrian army control."

He said the combination of Syrian ground troops and Russian air cover was proving extremely effective and predicted "big changes" that would change the battlefield by mid-year.