Iraqi forces and allied Sunni tribesmen repelled an overnight attack by the Islamic State (ISIS)  on a town between two militant-held cities in the western Anbar province, a tribal leader said Tuesday.

The militants launched an attack shortly before midnight Monday to try and capture the town of Khaldiya, which is between Fallujah and the provincial capital of Ramadi, Sheikh Rafie al-Fahdawi said.

He said the militants captured a small village outside Khaldiya. He said no troops or tribal fighters were killed in the clashes.

ISIS militants routed Iraqi troops and seized Ramadi over the weekend in their most significant advance since a U.S.-led coalition began airstrikes against the extremists last summer.

The latest advance prompted Prime Minister Haider al-Abadi to order Shiite militias to prepare to go into the restive Sunni province following a request from the local government and some tribes.

The paramilitary forces, known as Popular Mobilization Units, played a major role in dislodging ISIS militants from the northern city of Tikrit last month and rolling back the extremists elsewhere in the country.

But rights groups have accused the militiamen of carrying out revenge attacks against Sunnis and of looting and destroying property. Militia leaders have denied the allegations.

On Monday, the Islamic State militants searched door-to-door for policemen and pro-government fighters in Ramadi and threw bodies in the Euphrates River in a bloody purge.

Officials put the number of people killed since Friday at least 500, including civilians and security forces.