The UN Security Council has warned the referendum could potentially be destabilising.

“The referendum President Fuad Massum, nor is it in those of the [political] parties – it is in your hands,” Barzani told a large crowd at a soccer stadium in the regional capital Arbil.

“We say that we are ready for serious open-minded dialogue with Baghdad, but after September 25, because now it is too late,” he said.

Behind the scenes, negotiations are still taking place aimed at persuading Barzani to postpone any referendum, according to officials close to the discussions.

“Nothing is definitive yet. Discussions are continuing to try to offer him serious guarantees that will convince him to change his mind,” said one official who did not wish to be identified.

In Ankara, Turkey’s National Security Council, chaired by President Recep Tayyip Erdogan, slammed the planned referendum as “illegitimate”, indicating that Ankara was prepared to retaliate if it went ahead.

It warned that Ankara was prepared to use its “rights” in line with international agreement, with specifying what action it could take.

On the Iranian front, a commander of its elite Revolutionary Guards, Major General Qassem Soleimani, held talks with Barzani in Arbil.

“It’s his last visit before the referendum to advise Kurdish officials that Iran is seriously hostile to it and warn them to call it off,” a provisional source said.

Iran and Turkey both have sizeable Kurdish populations of their own and fear the vote in northern Iraq will stoke separatist aspirations at home.

The Iraqi government is also opposed to the referendum in the oil-rich Kurdish region, which it has called unconstitutional.

In 2014, after a dispute over oil exports, Baghdad suspended payments to Barzani’s Kurdish regional government, which equated to 17 per cent of Iraq’s national budget or US$12 billion, and provided 80 per cent of the region’s budgeted revenue.

Wages, including those of Kurdish peshmerga fighters, were slashed after those transfers ended.

“The Iranians are still pushing for negotiations between Kurdistan and Baghdad,” the source said.

Soleimani has told Kurdish officials that “Iran is pressuring Baghdad so it accepts Kurdish demands and solves the issues of the budget, peshmerga salaries and disputed areas”.

Iraqi Kurdistan has since 2003 been made up of the three provinces of Arbil, Dohuk and Sulaimaniyah, but its leaders have laid claim to other areas that are constitutionally under Baghdad’s authority, including the oil-rich province of Kirkuk.

The Iraqi Kurds would like these disputed areas to take part in the vote.

On Thursday, the UN Security Council warned that the referendum was “potentially destabilising”.

The council urged “dialogue and compromise” to address differences between the Iraqi government and the regional authorities.

It also said the vote could weaken the military campaign against Islamic State (IS), “in which Kurdish forces have played a critical role”.

Baghdad this week launched offensives to oust IS from the last two pockets it controls in Iraq.

Despite tensions over the referendum, Iraqi forces on Friday recaptured IS-held Sharqat on their drive to retake the nearby northern town of Hawija back from the jihadists.

On the political front, Prime Minister Haidar al-Abadi said earlier this week he rejected an independence referendum under any form, even non-binding. He said the poll was “rejected, whether today or in the future”.

On Wednesday, Saudi Arabia urged Barzani to cancel the referendum to avoid further “crises” in the region.

But the Iraqi Kurdish leader has refused to give in, and on Thursday rejected an initiative from Iraqi President Fuad Massum – himself a Kurd – for negotiations.

Massum, in a document seen by AFP, suggested starting UN-backed talks towards a deal with Baghdad.

In areas disputed between Arbil and Baghdad, some have issued strong warnings against the vote.

In the town of Tuz Khurmatu in the province of Salaheddine, an official from the Hashed al-Shaabi paramilitary umbrella group has said he will not allow the poll.

“We’re ready for a fight to the death,” said Atef Annajar, whose group is dominated by Iran-backed Shiite militias, adding however that “the leadership is trying to calm the situation”.

Hadi al-Ameri, head of the powerful Iran-backed Badr organisation, last week vowed to defend the unity of Iraq, warning that the poll could trigger partition and civil war.