London: As Islamic State's brutality grows each passing day, the terror organisation is now under attack from guerrillas itself, it has been reported.

Small groups of Syrians are hunting down the ISIS militants in their stronghold in eastern Syria in a new guerrilla campaign and aims to generate fear in ISIS ranks.

'White Shroud' - a group that claims to have killed more than 100 militant fighters in in attacks in Deir al-Zor province - is reference to the death shroud that awaits the Islamic State militants for their crimes against the innocent Syrian people, said the group leader who gave his name as Abu Aboud.

Aboud - not real name - was the commander of the anti-Assad insurgent group which was crushed by the better armed and financed ISIS earlier this year.

But the White Shroud now shows no mercy to the ISIS militants when the group manages to abduct them.

The Syrian Observatory for Human Rights says White Shroudis one of several small groups that have taken up arms against ISIS in Deir al-Zor province in recent months and are picking off ISIS fighters whenever they get the chance.