ANKARA (Reuters) - Turkish Foreign Minister Mevlut Cavusoglu said on Wednesday he had conveyed Turkey’s concerns about northern Iraq’s decision to hold an independence referendum to Iraqi Kurdish leader Massoud Barzani and his delegation.

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Turkey, along with Iraq, Iran and Syria, opposes the idea of Iraqi Kurdish independence, fearing separatism could spread to their own Kurdish populations. Turkey’s outlawed Kurdistan Workers Party (PKK) has waged a three-decade insurgency.

The United States and other Western nations fear the September vote could ignite a new conflict with Baghdad and possibly neighboring countries, diverting attention from the war against Islamic State militants in Iraq and Syria.

“Our expectation from Erbil is clear: that is the cancellation of the referendum as the interests and future of the Kurds lies in a united Iraq,” Cavusoglu told a news conference in Baghdad broadcast on Turkish television.

He spoke before traveling to Erbil, the capital of the Kurdistan region in northern Iraq.

Cavusoglu later told reporters he conveyed Turkey’s concerns to Barzani in a “sincere” meeting in which the two delegations discussed the referendum. Turkey did not impose any demands over the vote but urged dialogue between Erbil and Baghdad, he said.

Kurds have sought an independent state since at least the end of World War One, when colonial powers divided up the Middle East and left Kurdish-populated territory split between modern-day Turkey, Iran, Iraq and Syria.

Iraqi Prime Minister Haider al-Abadi’s government has rejected the referendum as “unilateral” and unconstitutional.

A delegation representing Iraq’s ruling Shi’ite coalition may meet Kurdish politicians again next week to try to convince them to delay or cancel the referendum plan, a negotiator told Reuters on Monday.

Turkish President Tayyip Erdogan told U.S. Secretary of Defense James Mattis on Wednesday that Turkey felt unease over U.S. support for the Syrian Kurdish militant group YPG.

A Pentagon spokeswoman said Mattis had expressed U.S commitment to bilateral ties with Turkey. Relations between the two NATO allies have deteriorated due to U.S. support for the YPG, which Turkey views as a terrorist group.

In a statement, the presidential sources said Erdogan and Mattis emphasized the importance of maintaining the territorial integrity of Syria and Iraq, as Kurdish northern Iraq gears up for an independence referendum in September.

Both Turkey and the United States have voiced concerns over the referendum.