Two units of Turkish special forces have crossed into northern Iraq in "hot pursuit" of the outlawed Kurdistan Workers' Party (PKK) militants after a deadly attack on the army.

“Turkish security forces crossed the Iraqi border as part of the hot pursuit of PKK terrorists who were involved in the most recent attacks," a Turkish government source said on Tuesday.

"This is a short-term measure intended to prevent the terrorists' escape," the source added.

Turkey’s Dogan news agency quoted unnamed military sources as saying that two battalions from Turkey's special forces crossed the border.

The move comes after at least 14 police officers were killed in a roadside bomb attack in eastern Turkey's Igdir Province earlier on Tuesday.

In a separate development on Tuesday, at least three Turkish police officers were reportedly killed in a rocket-propelled grenade attack by PKK militants on their armored vehicle in the town of Cizre, in the southeastern province of Sirnak.

Later in the day, the Sirnak governor’s office issued a statement on its official website, dismissing the report of police deaths as “baseless and incorrect.”

'Three or five terrorists'

Meanwhile, Turkish President Recep Tayyip Erdogan pledged to press ahead with attacks on the PKK militants.

Turkish President Recep Tayyip Erdogan (Photo by AFP)

“We did not and will not abandon the nation's future to three or five terrorists,” Erdogan said in a speech in the capital, Ankara, two days after a deadly attack on Turkish soldiers and police officers by the PKK militants in the Kurdish-dominated southeastern province of Hakkari.

“In this country, the burial mound for martyrs has never remained empty. It appears it will never remain empty,” said Erdogan, stressing that “with God's permission, Turkey, which has overcome plenty of crises, will get over the plague of terror.”

Erdogan said Turkey’s operations against the PKK have inflicted “serious damage” on the group at home and abroad.

According to official Anatolia news agency, over 50 Turkish warplanes took part in six-hour raids against the PKK positions in northern Iraq early on Tuesday, killing “35 to 40 terrorists according to preliminary findings”.

Ankara launched airstrikes against PKK positions in Iraq and Turkey as well as purported Daesh targets in Syria after a deadly July 20 bomb attack attributed to Daesh terrorists left 32 people dead in the southeastern Turkish town of Suruc, across the border from the northern Syrian town of Kobani.

A shaky ceasefire between Ankara and the PKK that had stood since 2013 was declared null and void by the militants following the Turkish airstrikes against the group.

The PKK has been fighting for an autonomous Kurdish region in southeastern Turkey since the 1984. The conflict has left tens of thousands of people dead.