Hundreds of Turkish-backed rebels in northern Syria are preparing to spearhead an imminent offensive against the Kurdish-held Afrin region in northern Syria, as part of Turkey's plan to clean that Syrian area from its Kurdish fighters, a monitor group reported on Friday.

The Ankara-backed rebels headed from the northeastern countryside of Aleppo into the Turkish territories to be transferred through the Turkish areas to the border points adjacent to Afrin, the target of an imminent Turkish operation to defeat the Kurdish People Defense Units, or YPG, which Turkey deems a terror group due to its links with the Kurdistan Workers Party, PKK.

The Syrian Observatory for Human Rights said the Afrin-based Russian posts have remained in that region, contrary to what some activists had said about the evacuation of Russian positions ahead of the anticipated Turkish campaign in Afrin.

The Observatory, which says it relies on a network of activists on ground, said the ground offensive could start at any minute from ten directions due to the massive Turkish military buildup on the Turkish-Syrian border near Afrin.

Earlier in the day, The YPG said Turkish artillery has heavily pounded the positions of the U.S.-backed Kurdish fighters in Syria's northern region of Afrin since midnight Friday.

The heavy Turkish shelling targeted several areas in Afrin and caused property losses, said the YPG.

"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 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 and its allies of the Syrian Democratic Forces (SDF), which are backed by the U.S. and led by 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 PKK.

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.