Baghdad (AFP) - Baghdad warned Ankara on Monday that time is running out to remove forces it sent to northern Iraq without permission, but Turkey indicated it was unlikely to do so.

Prime Minister Haider al-Abadi said there were "only 24 hours left" of the 48 that Iraq gave Turkey to remove tanks and soldiers sent to a base near Mosul.

And Abadi visited the country's air force headquarters, saying: "We must be prepared and ready to defend Iraq and its sovereignty," according to his office.

"The air force has the capability... to protect Iraq and its borders from any threat it faces," the premier said.

But despite the tough talk by Abadi, who is struggling to assert Iraq's sovereignty while receiving foreign assistance against the Islamic State group, Baghdad's air force is hopelessly outgunned by Turkey and its realistic recourse is limited to diplomacy.

A senior Turkish official said Monday that Ankara was unlikely to withdraw the forces, which number between 150 and 300 soldiers backed by 20 tanks, that were deployed to a base in the Bashiqa area, near IS's Iraqi hub Mosul.

"We expect them to remain," the official said, though "it will depend on discussions."

Iraqi Foreign Minister Ibrahim al-Jaafari clarified Monday that the demand for the withdrawal applied only to the recent deployment and not to Turkish trainers, who have been working with forces in the country's north for some time.

"The Iraqi demand (for the withdrawal) is only related to the violation recorded by the presence of Turkish armed forces without coordination with Iraq," Jaafari told a joint news conference with his German counterpart, Frank-Walter Steinmeier.

"The advisers are another issue; there are advisers from a number of countries and we accepted the principle of advisers, but not the principle of ground forces entering Iraqi territory," Jaafari said.

Turkish Prime Minister Ahmet Davutoglu has sought to downplay the recent deployment as "routine rotation activity" associated with the training effort, and as "reinforcement against security risks".

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- Oil smuggling allegations -

"This is not a new camp," but rather a pre-existing "training facility established to support local volunteer forces' fight against terrorism", Davutoglu said.

While Abadi has repeatedly said Iraq needs all the help it can get to fight IS, he is walking a fine line between receiving that support and projecting sovereignty.

Taking a strong stance on Turkey is what "Abadi has to do to avoid being thrown out of office and (to) stay alive," said Kirk Sowell, a Jordan-based political risk analyst who is the publisher of Inside Iraqi Politics.

"He is so weak, so under pressure on multiple fronts, and Shiite Arab opposition to the Turkish project so strong, he has no choice," Sowell said.

"Abadi is kept in office by divisions among his critics, but they would crucify him if he were seen as acquiescing in the foundation of either American or Turkish bases on Iraqi soil, anywhere in Iraq."

On Monday, Abadi joined Russia and Iran in linking Turkey with oil smuggling by IS, which overran large areas of Iraq last year and also holds major territory in neighbouring Syria.

During a meeting with Steinmeier, Abadi stressed the "importance of stopping oil smuggling by (IS) terrorist gangs, the majority of which is smuggled via Turkey," his office said.

Russia has accused Turkish President Recep Tayyip Erdogan and his family of involvement in the IS oil trade, to which he responded that Russia was in fact involved.

Iranian media then picked up Russia's claims, prompting Erdogan to lash out at his Iranian counterpart.

And Mohsen Rezaie, secretary of Iran's Expediency Council, said Iranian military advisers on the ground in Iraq and Syria had images of IS oil trucks going to Turkey.

The US has meanwhile said that IS oil smuggling through Turkey is not significant, prompting Moscow to accuse Washington of a cover-up.