Iraqi forces attacked a desert outpost of Daesh terrorists near the Syrian border Saturday in preparation for a drive up the Euphrates Valley towards the frontier, commanders said.

The assault targeted the former mining town of Akashat, in mainly Sunni Arab Anbar province some 100 kilometers (60 miles) south of the Daesh border bastion of Al-Qaim.

Al-Qaim and the Euphrates towns of Rawa and Anna downstream form just one of two enclaves still held by Daesh in Iraq after a string of battlefield defeats this year.

"The army, the Hashed al-Shaabi (Popular Mobilization Forces) and the border guard launched a major operation to liberate Akashat... and secure the border to its north," said the head of Joint Operations Command, General Abdelamir Yarallah.

The Hashed al-Shaabi are a paramilitary force largely composed of Iran-trained Shiite militias but also including some fighters recruited from Sunni tribes.

The offensive, supported by a US-led air alliance, is also aimed at tightening Iraq's hold on its border with Syria, a spokesman for Iraq's Joint Operations Command, Brigadier Yehia Rasool, said in a statement.

Iraqi commanders estimate there are no more than 300 civilian families left in Akashat, a former railhead that was once a major source of phosphate production.

Imed Meshaal, mayor of Rutba, a desert town further south recaptured from Daesh last year, told AFP the terrorists had turned the area into a major hub for arms caches, training camps and command centers.

Iraqi commanders say they estimate Daesh still has more than 1,500 fighters in its Al-Qaim enclave.

The terrorists also control a second enclave west of the ethnically divided Kurdish-held city of Kirkuk centered on the mainly Sunni Arab town of Hawija.

A promised offensive against Daesh in the oil-rich region has been delayed by a row over a controversial referendum on Kurdish independence planned for later this month.

Saturday's offensive follows a series of military setbacks suffered by Daesh in Iraq.

In July, Iraq retook control of Mosul, Daesh's key stronghold in the north, after a campaign of nearly nine months.

In August, Iraqi Prime Minister Haider al-Abadi declared victory over the terrorist group in Tal Afar, west of Mosul.