Fresh clashes refugees fleeing in Syria war

Monitoring group the Syrian Observatory for Human Rights said about 120 fighters on both sides had been killed around the town of Ratyan on Friday.

As many as 20,000 refugees fleeing the fighting have gathered at a border crossing with Turkey.

Turkey says it is prepared to help the refugees but the frontier is shut.

In the past few days, the Syrian army backed by Russian air power has made a series of gains in Aleppo province.

Syrian state TV said on Friday that pro-government forces had seized Ratyan, just north of Aleppo city.

Rebel chief Hassan Haj Ali told Reuters the town had not yet fallen but there were "very heavy battles".

"The regime is now trying to expand the area it has taken control of," he added.

"Now the northern countryside [of Aleppo] is totally encircled and the humanitarian situation is very difficult."

Earlier in the week, the Syrian government claimed a major victory by breaking the rebel siege of two towns in Aleppo province, severing an opposition supply line from Turkey to Aleppo city.

"It feels like a siege of Aleppo is about to begin," said David Evans, a spokesman for aid group Mercy Corps.

Before the civil war, Aleppo was a key commercial centre and home to more than two million people. Since 2012 it has been divided into rebel- and government-held areas.

The UN Office for the Co-ordination of Humanitarian Affairs (OCHA) said up to 20,000 people fleeing the fighting in Aleppo province had gathered at the Bab al-Salam border crossing on the Turkish border.

It said between 5,000 to 10,000 refugees had also fled to the nearby city of Azaz.

"Humanitarian organisations are responding to the needs of those displaced, but ongoing military conflict is making access to populations in need increasingly difficult," the UN's Linda Tom told AFP news agency.

In a televised speech, Turkish Prime Minister Ahmet Davutoglu said Turkey would not leave refugees "without food or shelter" but he would not say if they would be allowed in.

Nato has accused Russia of "undermining" Syrian peace efforts through its strikes, which it says are mainly aimed at opposition groups. Russia insists it only targets what it calls terrorists.

On Friday, Turkish President Recep Tayyip Erdogan accused Russia of being engaged in an "invasion" of Syria, saying it was trying to create a "boutique state" for ally President Bashar al-Assad.

Mr Erdogan said Russia and the Syrian government were together responsible for 400,000 deaths in Syria.

On Thursday Russia accused Turkey, key backer of Syria's opposition, of preparing a ground invasion, an accusation Mr Erdogan called "laughable".

Turkey and Russia have been embroiled in a row since Turkey shot down a Russian jet it accused of violating its airspace in November.