A main goal of the military operation was to recapture Tel Rifaat, a town southeast of Afrin, and a string of Arab villages the YPG captured from rebels in February 2016, driving out tens of thousands of inhabitants, Abdul Rahim said.
In pictures sent by Hasakeh to AFP, Kurdish Red Crescent rescuers could be seen retrieving bloodied bodies from a collapsed concrete structure and laying them on orange stretchers.
The Britain-based Syrian Observatory for Human Rights said a total of 18 civilians had been killed so far in the two-day operation.
The United Nations Security Council will hold talks about the situation in Syria on Monday, French Foreign minister Jean-Yves Le Drian said on his Twitter feed on Sunday.
Turkey's military has been shelling the Afrin region since Thursday, a move which it said was in response to fire coming from the area. Ankara denied any civilian casualties, with Cavusoglu accusing the YPG of sending out "nonsense propaganda and baseless lies".
Afrin is an enclave of YPG control, cut off from the longer strip of northern Syria that the group controls to the east extending to the Iraqi border, where there is an American presence.
It earlier said it had taken out 153 targets belonging to Kurdish militants, although it is unclear if this includes Sunday's figures. "We are only after terrorists".
The Turkish military said its air force destroyed 108 targets in seven regions during the operation, including weapons depots and barracks belonging to Kurdish militias and ISIS.More news: Cuomo: NY flu cases spike, 1600 hospitalized in the past week
Washington has called the terrorist group a "reliable ally" in its fight against Daesh in Syria even though its mother organization, the PKK, is listed as a terrorist group by Turkey, the US, and the European Union, having waged a terror campaign against Turkey for more than 30 years, killing almost 40,000 people.
President Recep Tayyip Erdogan has repeatedly threatened over the last days to launch a ground operation, also including pro-Ankara Syrian rebels, to oust the YPG from Afrin and the area. We aim to encircle the city and ensure the militias are evicted.
It was being carried out under the framework of Turkey's rights based on global law, UN Security Council's decisions, self-defense rights under the UN charter and respect to Syria's territorial integrity, according to Turkish military.
Iran's foreign ministry said Sunday it "expects all countries, especially the Turkish government as one of the guarantor states [of the Astana Process].to continue to play a constructive role and carry out its responsibility to resolve the crisis in Syria diplomatically".
But the YPG has been the key ally of Turkey's fellow North Atlantic Treaty Organisation member the United States in the fight against Islamic State jihadists, playing a key role in pushing the extremists out of their Syrian strongholds.
"Turkey has used its right under global law", said Bozdag, who is the top government spokesman, refusing to be drawn on how long the operation would take.
In mid-afternoon on Saturday the Turkish air strikes began, with plumes of smoke rising above Afrin.
A 30,000-strong, US-trained border force from the Syrian Democratic Forces, dominated by YPG fighters, is to be trained in Manbij. The militia forms the backbone of the Syrian Democratic Forces, the main USA ally against the Islamic State group in Syria.