The Free Syrian Army (FSA) rebel group has entered the city centre of Afrin, which had been controlled by Kurdish fighters, according to FSA spokespersons and Turkish media.

Clashes between the opposing sides were ongoing on Sunday morning, privately-owned Dogan News Agency and FSA spokespersons said early on Sunday.

Videos and photos shared by the Turkish-backed FSA fighters on social media showed them in residential streets, making victory signs and waving flags. Al Jazeera cannot independently confirm their authenticity.

Turkey - together with the FSA rebel group - in January launched an air-and-ground operation into Afrin in the northwest of Syria to vanquish the US-backed Kurdish People's Protection (YPG) fighters near its border.

Turkey considers the Kurdish Democratic Union Party (PYD) in Syria and its armed wing YPG to be "terrorist groups" with ties to the banned Kurdistan Workers' Party (PKK).

The PKK has waged a decades-long armed fight against the Turkish state that has killed tens of thousands of people.