Iraqi forces on Friday (November 3rd) recaptured an important crossing on the border with Syria from the "Islamic State of Iraq and Syria" (ISIS) as they advanced into the group's last stronghold in Iraq.

Iraq's Joint Operations Command said troops had "regained full control" of the Husaybah border post on the edge of al-Qaim after launching an operation to oust ISIS from westernmost Anbar province.

Prime Minister Haider al-Abbadi released a statement congratulating the armed forces for "entering into al-Qaim and liberating" the border crossing.

An Iraqi army officer said the group's fighters "deserted the border post after several of them were killed" and headed towards the Syrian town of Albu Kamal, directly across the border from al-Qaim.

Across the border in Syria, ISIS has been driven from most of its strongholds in Deir Ezzor, but still controls over 35% of the province, much of it empty desert.

Its last major position is the border town of Albu Kamal, though it also holds a string of smaller towns and villages and at least one oil field, according to the Syrian Observatory for Human Rights.

In Deir Ezzor province, ISIS is under attack by the Syrian Democratic Forces (SDF) and the Syrian regime, which on Friday announced it had expelled the last ISIS remnants from Deir Ezzor city.

Iraqi forces entered al-Qaim on Friday, military commanders said, unleashing a barrage of artillery fire along with Iraqi and coalition airstrikes.

Troops from the army and the elite Counter Terrorism Service "have started the assault on the centre of al-Qaim", Iraqi army 7th Division Commander Maj. Gen. Noman Abed al-Zobai said from the scene.

They have stormed the areas of al-Karabla, Saada and Husaybah, the Ministry of Defence said in a statement.

Al-Qaim and the surrounding areas are the last remnants of the self-styled caliphate ISIS declared after rampaging across Iraq and Syria in 2014.

Iraqi forces backed by coalition airstrikes launched the operation last week to seize back the strategically located pocket of desert along the Euphrates river.