Iraqi Prime Minister Haider al-Abadi is set to meet Iran's leaders for talks on regional security, including the future of Iraq's Kurdish region and the role of the Tehran-backed Shia militias in his country.

Abadi's meeting on Thursday with Iran's President Hassan Rouhani marks his second visit to Tehran in four months, highlighting his effort to rally support behind the central government in Baghdad.

There was no confirmation if Abadi will also meet Iran's Supreme Leader Ayatollah Ali Khamenei, although analysts said it would be likely.

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The trip follows his visit on Wednesday to Turkey, where he met President Recep Tayyip Erdogan and Prime Minister Binali Yildirim, and reaffirmed their stance against the Kurdish independence vote.

Earlier on Wednesday, the Kurdish Regional Government (KRG) proposed to freeze the outcome of the referendum, and open talks with Baghdad, while calling for an "immediate ceasefire and cessation of military operations" in the Kurdish region of Iraq.

The KRG proposal came just days after Iraqi forces took control of the Kurdish-held Kirkuk, with the support of the Shia militia, the Popular Mobilisation Units.

The proposal was rejected by Iraq's central government and Turkey, demanding instead for an outright annulment of the referendum result - the results of which overwhelmingly supported Kurdish independence.

Abadi's trip to Iran on Thursday is seen as a continuing effort to bolster Baghdad's call for a unified Iraq.

Mahjoob Zweiri, Associate Professor in Contemporary History of the Middle East at Qatar University, said he expects more military cooperation between Iraq and Iran, following Abadi's visit.

"There [are] very strong bilateral relations between Baghdad and Tehran since 2003," Zweiri, an expert on Iran, told Al Jazeera.

Zweiri cited Iran's role in Iraq's successful effort to defeat and drive out the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group from Mosul and other parts of Iraq.

The Tehran-backed Popular Mobilisation Unit fought alongside the Iraqi forces in fighting ISIL. On Monday, during his meeting with US Secretary of State Rex Tillerson, Abadi rejected the US call for the Shia militia to leave Iraq, saying it is "part of the Iraqi institutions".

Zweiri also said that showing solidarity towards Baghdad on the Kurdish question also serves Tehran's interest in the region.

He said that an independent Iraqi Kurdish region, which is backed by Israel, "is not something Iran wants to see".

Saudi influence in Iraq

Seyed Mohammad Hashemi, a Tehran based journalist, told Al Jazeera that aside from the discussion on the Kurdish issue and the Kirkuk offensive, he expects Abadi to "carry a message on behalf of the US administration" about the Iran nuclear deal and the possibility of further negotiations.

In recent weeks, US President Donald Trump had announced that he will no longer certify that Tehran is in compliance with the nuclear deal, and called on allies to renegotiate the deal.

Hashemi also said that with the upcoming Shia Muslim holiday of Arbaeen, a time when many Iranian pilgrims travel to Iraq, he expects Abadi to discuss security measures and coordination. In the past, Shia religious events and holy sites in Iraq have been targeted with deadly suicide attacks and bombings.

Meanwhile, Hashemi dismissed speculations that Saudi Arabia may be drawing Iraq from Iran's geopolitical orbit, following Abadi recent visits to Riyadh.

"I don't think Iran is very much concerned about Saudi Arabia's role in Iraq," he said.

"That is because the commonalities between Iranian and Iraqi people in social, cultural and religious spheres are great and already profound."

"We have heard Saudis want to play a role in Iraq's reconstruction," he said.

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"However, I don't think the Saudis, who have their own problems with their ambitious economic plan, will be able to fulfil pledges they made to Baghdad," Hashemi said.

Zweiri, the Doha-based scholar of Iranian politics, agreed with Hashemi's assessment on the Iraq-Saudi relations saying that "there's loads of obstacles and mistrusts" between the two countries.

"I don't think the normalisation between Baghdad and Riyadh will happen quickly," he said, adding that among the Iraqi political establishment, there is still many "who are not keen to develop relations with Saudi Arabia".