"Afrin people suffer material damage as artillery and missile attacks continue unceasingly," the YPG said. It added that it will respond strongly to the Turkish attack.

The YPG said the Turkish move marked the beginning of an anticipated military campaign in Afrin.

On Friday, Turkish Defense Minister Nurettin Canikli said Turkey's operation in Afrin region has "de facto" begun with cross-border shelling.

Canikli has previously said that his country will start an operation in Afrin without delay.

The battle of Afrin has been long anticipated, as Turkey made it clear it was going to unleash an offensive along with the Ankara-backed Syrian rebels against the YPG in Afrin in the northern countryside of Aleppo province in northern Syria.

Turkey deems the YPG as a terror group, part of the Kurdistan Workers Party (PKK).

The intensified shelling comes as Turkish officials said the Ankara-backed Syrian rebels were ready to start the offensive on Afrin.

Activists said a unit of the Turkish-backed Free Syria Army (FSA) moved from the northeastern countryside of Aleppo toward the border town of Rai as a prelude to their entry to the Turkish territories before being transferred to the frontlines to fight the Kurds in Afrin in the northwestern countryside of Aleppo.

The U.S. has urged Turkey not to move its forces to fight the Kurds in Afrin, while the Syrian government has warned it would shoot down any Turkish warplane fighting in Afrin.

Turkey's military operation in Afrin will deal a strong blow to the Kurdish fighters and weaken their growing influence in northern Syria near Turkey.

Ankara fears the separatist sentiment of Syria's Kurds could inspire Turkey's 14 million Kurds. Enditem