Syria oppn slams US for undermining it

Syrian rebels have killed 28 soldiers during attacks on army checkpoints in Idlib province. (AAP)

Syrian rebels have killed 28 soldiers during attacks on army checkpoints in Idlib province. (AAP)

Syria's main opposition group in exile has slammed the US for calling for an overhaul of the different groups opposing the Assad regime.

Syria's main opposition group in exile has accused Washington of undermining the country's revolution by seeking to overhaul how regime opponents are organised.

Two days ahead of key opposition talks in Qatar, the Syrian National Council (SNC) has lashed out at US criticism of the group for not being fully representative of Syria's diverse dissident groups.

"Any discussions aimed at passing over the Syrian National Council or at creating new bodies to replace it are an attempt to undermine the Syrian revolution by sowing the seeds of division," the SNC said in a statement on Friday.

US Secretary of State Hillary Clinton voiced frustration with the SNC this week, calling for a new more expansive opposition that would include more activists from inside Syria.

"There has to be a representation of those who are on the front line fighting and dying today to obtain their freedom," Clinton said during a tour of the Balkans, insisting the SNC "can no longer be viewed as the visible leader of the opposition".

Talk of an overhaul "is a sign of a lack of seriousness of the forces meant to support the Syrian people who are facing the murderous regime" of President Bashar al-Assad, the SNC said.

Reacting to accusations it is not inclusive, the group said it had grown from 280 to 420 members, that a third of its members are on-the-ground activists and that 15 per cent of its members are women.

The SNC said on Thursday it had received $US40.4 million ($A39.01 million) in international aid since it was set up a year ago, half of which came from Libya and the rest mainly from Qatar and the United Arab Emirates.

Washington has accused the SNC of failing to unite the resistance to Assad's regime beyond a small group of Syrian exiles, some of whom Clinton said have not set foot in their homeland "for 20, 30 or 40 years".

Clinton also warned of radical Islamists trying to "hijack" the revolution, prompting SNC chief Abdel Basset Sayda to blame the international community's failure to act for the rise in extremist sentiment.

Meanwhile Syrian rebels have taken full control of a strategic crossroads in the northwest that further limits the government's ability to reinforce its troops in second city Aleppo, a watchdog said on Friday.

Rebel fighters forced troops to pull back from their last position in the Saraqeb area where the main highways to Aleppo from Damascus and from the Mediterranean coast meet, the Syrian Observatory for Human Rights said.

The rebels now control an area extending 25 kilometres in all directions from the town, the Britain-based watchdog said.

"The army has withdrawn from its last checkpoint in the Saraqeb area," Observatory director Rami Abdel Rahman told AFP.

On Thursday, the army had already lost control of all but three checkpoints in the area.

The rebels killed at least 28 soldiers during its offensive in the area, the Observatory said. Video footage that appeared to show some soldiers being summarily executed drew condemnation from international human rights groups.

The rebels had already seized the town of Maaret al-Numan, further south on the Damascus-Aleppo highway, on October 8, in a first blow to the government's ability to resupply its troops in the northern metropolis where fierce fighting has raged since July 20.

Army shelling of rebel-held neighbourhoods of Aleppo killed a young girl early on Friday, the Observatory said.

The watchdog, which bases its reports on a network of activists, lawyers and medics at military and civilian hospitals inside Syria, says more than 36,000 people have been killed since the uprising against Assad's rule broke out in March last year.