More than 2,000 Syrians, including two defecting generals, have fled to Turkey amid escalating clashes in Syria's northern city of Aleppo, the Anatolia news agency reported on Wednesday.

The latest group of some 2,400 people brought the number of Syrian refugees in Turkey to around 50,000.

The two defecting generals were flanked by 35 officers including two colonels, said Anatolia.

This week has seen an increase in the number of refugees crossing into Turkey as violence has escalated in neighbouring Syria.

Syrian tanks stormed a rebel-held district of Aleppo on Wednesday, sparking fierce clashes that a security official said marked the start of a long-threatened ground assault on the key battleground city.

In addition to taking in refugees, Turkey is providing sanctuary to Syrian military defectors in a separate camp near the border where security is tighter.

Senior Syrian officers have been crossing into Turkey to link up with the rebel Free Syrian Army on an almost daily basis in recent months, often accompanied by rank-and-file troops.