A batch of 75 gunmen newly trained by US and coalition forces in Turkey to fight terrorist groups have entered northern Syria.

A batch of 75 gunmen newly trained by US and coalition forces in Turkey to fight terrorist groups have entered northern Syria, a monitoring group told AFP on Sunday.

"Seventy-five new fighters trained in a camp near the Turkish capital entered Aleppo province between Friday night and Saturday morning," said Rami Abdel Rahman, director of the UK-based opposition Syrian Observatory for Human Rights.

He said the group had entered in a convoy of a dozen cars with light weapons and ammunition, under air cover from the US-led coalition that has been carrying out air strikes against the so-called 'Islamic State of Iraq and the Levant' (ISIL) takfiri group in Syria and Iraq.

The fighters then deployed to support two US-backed units, with most assigned to Division 30 -- the main unit for US-trained fighters -- and others to a group called Suqur al-Jabal (Falcons of the Mountain).

Before the new batch of fighters, the US-led train-and-equip program had only managed to identify and train some 60 gunmen to fight ISIL terrorists on the ground.

The $500 million program run out of Turkey has been fraught with problems, with more than a dozen of those already deployed with Division 30 either dead or kidnapped.