Turkish President Recep Tayyip Erdogan has called the upcoming referendum on Kurdish independence on Iraq “wrong” and “a threat to the territorial integrity of Iraq,” despite his country’s friendly ties with the Kurdistan Regional Government (KRG).

“The [referendum] statement by the northern Iraqi authority in Iraq deeply saddened us,” the president told his Islamist Justice and Development Party (AKP) lawmakers Tuesday, according to the Turkish newspaper Hurriyet.

Erdogan accused the Iraqi Kurdish leadership of failing to properly take Baghdad’s concerns into consideration. “We would wish that these steps would be taken as a result of consultations. We have always defended the territorial integrity of Iraq. A step in such a crucial process does not serve anybody’s interest,” he asserted. “A step toward the independence of northern Iraq is a threat to the territorial integrity of Iraq, and it is wrong.”

The Kurdish outlet Rudaw carries more of his remarks, including his concern that a Kurdish government will not properly care for Arabs or Turkmen within KRG territory: “Arabs in Mosul and Turkmen and in Kirkuk live together with Kurds.”

The Turkish Foreign Ministry previously called a referendum on Iraqi Kurdish independence a “grave mistake” and called the unity of Iraq “one of the basic principles of Turkey’s Iraq policy.” Prime Minister Binali Yildirim also complained that “we have enough issues to deal with” without an independent Kurdistan. The referendum, he alleged was “wrong and an irresponsible decision.”

KRG President Masoud Barzani announced last week that his government, based in northern Erbil, would hold a referendum soon on whether Kurdistan should be a sovereign country. The KRG Peshmerga are a key force in the war against the Islamic State, but the majority-Sunni Kurds have increasingly clashed with the Shiite government in Baghdad.

Baghdad issued a statement condemning the referendum, arguing, “No party can decide its fate unilaterally… All Iraqis should have their say regarding their homeland’s fate.”

The United States, meanwhile, said in a State Department statement that the KRG had “legitimate aspirations” to independence but that holding a referendum amid the ISIS fight would distract from “more urgent priorities” at the moment. American officials had previously referred to Kurdish independence as a matter of “not if, but when.” Reports suggest, “Washington will likely do nothing to actively oppose Iraqi Kurdish independence, nor will it overtly encourage it.”

The referendum has derailed otherwise cordial relations between the KRG and Turkey. While the Turkish government stands in vocal opposition to the interests of the Syrian Kurdish People’s Democratic Union (PYD) and has imprisoned dozens of pro-Kurdish politicians in Turkey, Ankara and Erbil have strong economic ties and have maintained peaceful relations.

Barzani visited Erdogan in February to discuss both those ties and the war against the Islamic State. Barzani’s government has long opposed the U.S.-designated terrorist group the Kurdistan Workers’ Party (PKK) with which the PYD has contact. Turkey considers the two groups the same entity, while the United States cooperates with the PYD in the war on the Islamic State in Syria. Barzani has said the PYD and PKK “are exactly one and the same thing.”

Barzani’s nephew, Prime Minister Nechirvan Barzani, has threatened to attack the PKK in northern Iraq if they refused to leave the area. Despite this, PKK-affiliated Kurdish leaders have supported the KRG’s independence referendum. “The referendum is a democratic right, and no one should stand against it,” the head of the PKK-affiliated Group of Communities in Kurdistan (KCK) Cemil Bayik told reporters Tuesday.

The Kurds of Iraq will vote on their independence on September 25, 2017.