ISTANBUL — Turkish President Recep Tayyip Erdogan said Sunday that his country had begun operations in Iraq's Sinjar region, an area where it had threatened cross-border military action.

The announcement came two days after sources said Kurdish PKK militants would withdraw from Sinjar. The PKK, or Kurdistan Workers Party, has waged an insurgency against the Turkish state for decades.

"We said we would go into Sinjar. Now operations have begun there. The fight is internal and external," Erdogan told a crowd in the Black Sea province of Trabzon, without elaborating on what operations he was referring to.

Iraq's Joint Operations Command denied that any foreign forces had crossed the border into Iraq.

"The operations command confirmed that the situation in Nineveh, Sinjar and the border areas was under the control of Iraqi security forces and there is no reason for troops to cross the Iraqi border into those areas," it said in a statement.

But Erdogan said last week the PKK was creating a new base in Sinjar — about 75 miles west of Mosul — and that Turkish forces would attack if necessary.

Sources in northern Iraq said Friday the PKK would withdraw from Sinjar, where it gained a foothold in 2014 after coming to the aid of the Yazidi minority community, who were under attack by Islamic State militants.

In October, Iraqi government forces launched an offensive to retake the area in response to a Sept. 25 referendum on Kurdish independence, which Baghdad opposed.

The PKK is considered a terrorist organization by Turkey, the European Union and the United States. For decades, it has been based in Iraq's Qandil mountain range, near the border with Iran.

Turkish troops and their rebel allies swept into northwest Syria's Afrin town this month, the culmination of an eight-week campaign to drive Syrian Kurdish YPG fighters from the region. Turkey sees the YPG as terrorists and an extension of the outlawed PKK.

Erdogan has vowed to extend the military operation along the Syrian border and on Sunday said the Turkish-led forces would take control of the town of Tel Rifaat.

Many civilians and YPG fighters have gathered in and around Tel Rifaat after Turkey seized control of Afrin. The Kurdish-controlled enclave is cut off from a larger expanse of Kurdish territory in the northeast of Syria.

The United Nations said last week that around 75,000 people had been displaced to Tel Rifaat and surrounding areas from Afrin, and more were expected to come.