Iraqi forces have launched an operation to clear the desert bordering Syria of ISIS, in a final push to rid the country of the terrorist group, the military said.

Troops from the Iraqi army are searching a large strip of border land where ISIS terrorists are thought to be hiding after being ousted from its former strongholds.

Earlier this week, both the Iraqi Prime Minister and the President of neighbouring Iran declared that ISIS had been defeated.

Military efforts: Iraqi forces have begun a clear-out of the desert bordering Syria of ISIS, in a final push to rid the country of ISIS fighters (not pictured)

On Tuesday, Iranian President Hassan Rouhani on Tuesday declared 'victory' over ISIS in a televised speech, thanking the armed forces of Iraq and Syria for 'the end of this group that brought nothing but evil, destruction, murder and savagery'.

He congratulated Iran's Revolutionary Guards and its foreign arm the Quds Force for a 'great victory' but insisted that the 'main work was accomplished by the people and armies of Syria, Iraq and Lebanon'.

On the same day. Iraqi Prime Minister Haider al-Abadi said that while ISIS had been defeated from a military perspective, but he would only declare final victory after all its fighters were tracked and rooted out.

Iraqi forces on Friday captured the border town of Rawa, the last remaining town under Islamic State control, signalling the collapse of the group's 'caliphate' proclaimed after it overran much of Iraq's north and west in 2014.

Iraqi army commanders say the military campaign will continue until all the frontier with Syria is secured to prevent Islamic State from launching cross border attacks.

Defeated: The remnants of ISIS are believed to be hiding in the desert near the border of Iraq and Syria, Iraqi military says

'The objective behind the operation is to prevent remaining Daesh groups from melting into the desert region and using it as a base for future attacks,' said army colonel Salah Kareem, referring to Islamic State by an Arabic acronym.

'We will completely secure the desert from all terrorist groups of Daesh and declare Iraq clean of those germs,' said army Brigadier General Shakir Kadhim.

Once the desert operations end, Prime Minister Abadi is expected to officially announce the final victory over Islamic State in Iraq, said official sources.

Army officials said troops advancing through sprawling desert towards the Syria border are facing landmines and roadside bombs placed by retreating militants.

'We need to clean scattered villages from terrorists to make sure they no longer operate in the desert area with Syria,' said army Lieutenant colonel Ahmed Fairs.

Iraqi military helicopters provided cover for the advancing troops and destroyed at least three vehicles used by Islamic State militants as they were trying to flee a village in the western desert, said the army officer.

Russian President Vladimir Putin, Turkish President Recep Tayyip Erdogan, and Iranian President Hassan Rouhani pose during a trilateral meeting on Syria in Sochi

ISIS's self-declared caliphate collapsed in effect in July, when U.S.-backed Iraqi forces captured Mosul, the group's de-facto capital in Iraq, after a grueling battle that had lasted nine months.

Driven also from its other bastion in Syria's Raqqa, ISIS has since been gradually squeezed into an ever-shrinking pocket of desert straddling the Syria-Iraq frontier by a range of enemies that include most regional states and global powers.

The group's leader, Abu Bakr al-Baghdadi, is believed to be hiding in the stretch of desert which runs along the border of both countries.

Meanwhile, the leaders of Russia, Iran and Turkey have met to boost the peace process in neighbouring Syria ahead of another round of UN talks in Geneva.

Russian President Vladimir Putin met with Iranian President Hassan Rouhani and Turkish President Recep Tayyip Erdogan in Sochi on Wednesday, and spent hours discussing Syria.

Syria is divided between forces loyal to Kremlin-allied strongman Assad, the US-backed Syrian Democratic Forces (SDF) and several jihadist groups and rebel units.

With regime forces having gained the upper hand on the battlefield with Russia's help, including recent victories against the ISIS group and a new drive against rebels near Damascus, Putin is hoping the timing is right after years of failed peace bids.

Moscow, Ankara and Tehran are now cooperating with increasing intensity on ending the civil war, even though Turkey backs the rebels and is technically at odds with Russia and Iran.