Ankara launched an air strikes campaign across Iraq and Syria on Sunday as part of Operation Claw-Sword following a bombing in Istanbul on November 13 that killed six people.

"Our operations with planes, cannons and drones are only the beginning. Our determination to secure all our southern border... with a safe zone is stronger today than ever before," President Recep Tayyip Erdogan told lawmakers in parliament.

"While we press ahead with air raids uninterrupted, we will crack down on terrorists also by land at the most convenient time for us," he told lawmakers from his AKP party.

Turkey blamed the Istanbul attack on the Kurdistan Workers' Party (PKK), which is blacklisted as a terror group by the European Union and the United States.

The PKK, which has waged an insurgency against the Turkish state since 1984, denied any role in the bombing -- the deadliest in five years after a spate of attacks in Turkey between 2015 and 2017.

Turkey has intensified air raids and artillery fire on the PKK and the Kurdish People's Protection Units (YPG) targets in northern Iraq and Syria.

Ankara considers the YPG a terror group linked to the PKK. But the YPG -- the dominant force within the US-backed Syrian Democratic Forces (SDF) is seen as crucial in the fight against the Islamic State (IS) extremist group.

- 'Can't keep their word' -

The YPG denied a role in this month's attack.

A Kurdish military official told AFP that a Turkish drone strike hit a Kurdish position inside a Russian base in northeastern Syria on Wednesday killing one Kurdish fighter and wounding three.

The casualties were all fighters of the Kurdish-led SDF, the SDF officer said.

Erdogan accused Western states backing Kurdish forces in Syria of failing to deliver on their promise of no attacks on Turkish soil, pointing to the Istanbul bombing.

"If they can't keep their word," he said, "then we have the right to take care of ourselves."

Russia and the United States have called for de-escalation.

Nuri Mahmoud, YPG spokesman, late Tuesday deplored "the timid and weak statements by the guarantor countries and International Coalition" which relied on the group to counter IS jihadists.

Erdogan has repeatedly called for a 30-kilometre (19-mile) "safe zone" to protect Turkey against cross-border attacks from Syrian territory.

On Wednesday, he vowed Turkey would complete the zone "step by step" starting from the towns of Tal Rifaat, Manbij and Ayn al-Arab, also known as Kobane in Kurdish, which are all located in northern Syria.

Kobane, a Kurdish-majority town near the Turkish border, was captured by IS in late 2014 before Syrian Kurdish forces drove them out early the following year.

A Turkish official told AFP the air campaign was "likely to continue for a while" and when the conditions were ripe, Turkish troops inside Syria would start the land incursion, referring to the presence of Turkish military units on the Syrian side of the border for three years.

Ankara has launched waves of attacks on Syria since 2016 targeting Kurdish positions as well as IS jihadists.

- Gas plant -

Turkish Defence Minister Hulusi Akar said the military had hit 471 Kurdish targets across Iraq and Syria as part of its latest offensive, adding "254 terrorists were neutralised."

A British-based monitoring group and Kurdish authorities have reported Turkish drone strikes on many locations in Hassakeh province including a domestic gas plant and an oil pumping station.

Turkish artillery fire also hit near the Jerkin prison in Qamishli, which holds Islamic State group detainees, according to both sources.

Akar insisted Wednesday that Turkey's military campaign targeted only "terrorists" and their structures.

"We have no problem with any ethnic or religious group, with our Kurdish or Arab brothers."

Turkish border towns have come under rocket fire from Syria in recent days. At least three people, including a child, were killed in a Turkish border town on Monday.

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