Beirut: Rebels in northern Syria were under attack on multiple fronts Monday from Russian-backed regime forces advancing Kurdish militia and Islamic State group jihadists.

One week into an assault on opposition-held areas of Aleppo province that has caused tens of thousands to flee troops loyal to President Bashar al-Assad have seized a string of villages.

Aided by Russian air strikes and allied militia including Lebanese Shiite group Hezbollah regime troops are now around 20 kilometres (14 miles) from the Turkish frontier.

"It's the first time since 2013 that the Syrian regime has been this close to the Turkish border in Aleppo province" said Rami Abdel Rahman head of the Syrian Observatory for Human Rights a British-based monitor.

Opposition fighters are now squeezed "between the pincers of the army which is pushing north Kurdish forces coming from the west and IS which dominates the east" he said.

The regime offensive one of the largest yet in the north has cut a major rebel supply route out of Aleppo city.

Regime forces now have their sights set on taking Tal Rifaat one of three remaining rebel bastions north of Aleppo city.

With their capture of the village of Kafeen late Sunday government troops are stationed only five kilometres (three miles) south of Tal Rifaat.

A rebel spokesman blamed the losses of villages in Aleppo province on the lack of support from regional powers opposed to Assad.

- 'Rebel areas collapsing' -

"The difference between them and us it's that we don't benefit from the help of our allies while the regime gets all sort of support from its allies" said Haitham Hammo a spokesman for Jabha Shamiya (Levant Front).

"This means the areas held by the revolutionaries are collapsing" he told AFP.

Since fighting intensified there in 2012 Aleppo province has been transformed into a patchwork of territories held by the government rebels Kurds and jihadists.

In the province's north opposition fighters are centred in three main strongholds: Tal Rifaat Marea -- under attack by IS -- and Azaz which lies five kilometres from the Turkish border.

All three towns fell to opposition fighters in 2012 just a year after the popular uprising against Assad's rule erupted.

But in recent weeks developments around Syria's second city Aleppo have put serious pressure on rebels there.

On Sunday night Kurdish fighters took control of three villages east of Afrin after clashes with rebels who were urged to leave by residents to avoid Russian air strikes Abdel Rahman said.

The Kurds are one of the most powerful fighting forces on the ground in Syria and have scored significant victories against IS.

- 'What peace negotiations?' -

About 350000 civilians are now stuck in the opposition-held eastern parts of Aleppo city bombarded daily by government forces.

On Monday 10 civilians were killed in an air strike on the rebel-held Salhin neighbourhood of the city according to the Observatory.

With the city nearly completely surrounded the fear is that residents of opposition-held areas will face severe shortages of basic goods.

"What peace negotiations are they talking about when the regime is transforming the people here into human remains?" said Abu Ahmad a resident of Aleppo.

Peace talks in Geneva quickly collapsed last week amid rebel anger over the government offensive.

Further north in the Shiite villages of Nubol and Zahraa where regime forces recently broke a three-year rebel siege steady transport routes with Damascus have finally resumed an AFP journalist said.

Three people were killed there Monday when rebels nearby fired rockets into the villages according to the Observatory.

If rebels lose Aleppo it would be a major turning point in the nearly five-year war which has left more than 260000 people dead.

In Damascus province regime forces began a siege of the rebel bastion of Daraya over the weekend prompting the opposition National Coalition to warn Monday of an "imminent massacre".

AFP