Turkey says its forces have seized designated targets on the second day of an offensive against a Kurdish militia in Syria, after a withdrawal by US forces opened up a dangerous new phase in the region's eight-year-old conflict.
Senior members of US President Donald Trump's own Republican Party condemned him for making way for the incursion and abandoning Syrian Kurds, who have been loyal allies of Washington in the fight against Islamic State in Syria.
NATO-ally Turkey has said it intends to create a "safe zone" for the return of millions of refugees to Syria. But world powers fear Turkey's action could deepen the conflict, and runs the risk of Islamic State prisoners escaping from camps amid the chaos.
The Kurdish-led authority in northern Syria said a prison struck by Turkish shelling holds "the most dangerous criminals from more than 60 nationalities" and Turkey's attacks on its prisons risked "a catastrophe".
The Kurdish-led Syrian Democratic Forces (SDF) holds thousands of Islamic State fighters and tens of thousands of their relatives in detention.
Turkey regards the Kurdish militia as a terrorist group because of its links to Kurdish PKK militants waging a decades-old insurgency in southeast Turkey.
"Our heroic commandos taking part in Operation Peace Spring are continuing to advance east of the Euphrates (river)," the Defence Ministry wrote on Twitter.
"The designated targets were seized," it later said.
In the Turkish border town of Akcakale, around 30 vehicles carrying Syrian rebels, many pick-up trucks mounted with anti-aircraft machines drove along the main along the Turkish side of the border from Syria's Tel Abyad. They were accompanied by some 10 Turkish military armoured vehicles.
Turkish forces shelled targets near Ral al Ain on Thursday morning, and SDF fighters responded, a witness said.
The Turkish military has hit 181 targets of the Kurdish militia with its air force and artillery since the start of operation into northeast Syria, the ministry said.
Turkish President Tayyip Erdogan's communications director, in an article published hours before the offensive started, said Trump had agreed to transfer leadership of the international campaign against Islamic State to Turkey.
President Trump called the Turkish assault a "bad idea" and said he did not endorse it.
Troops entered Syria at four points, two of them close to Tel Abyad and two close to Ras al Ain further east, according to Turkish media reports.
Air strikes killed at least five civilians and three SDF fighters, while dozens of civilians were wounded, the SDF said.
Thousands of people fled Ras al Ain towards Hasaka province, held by the SDF.
SDF spokesman Mustafa Bali said the group's fighters had repelled a ground attack by Turkish troops in Tel Abyad.
The United Nations Security Council will meet on Thursday to discuss Syria at the request of the five European members, Britain, France, Germany, Belgium and Poland.
The 22-member Arab League also said it will hold an emergency meeting on Saturday.
On Wednesday Trump defended US policy towards Kurds, saying it had sent them "tremendous amounts" in arms and funds.
"The Kurds are fighting for their land...As somebody wrote in a very powerful article today, they didn't help us in the Second World War, they didn't help us with Normandy as an example... But they were there to help us with their land, and that's a different thing," Trump said.
But one of Trump's closest fellow Republican allies, Senator Lindsey Graham, said failing to support the Kurds would be "the biggest mistake of his presidency".
The Syrian Kurdish group was for years one of Washington's main allies in Syria and the incursion was potentially one of the biggest shifts in years in the Syrian war that has drawn in global and regional powers.
The Kurds played a leading role in taking territory from IS, and now hold the largest swathe of Syria outside of the hands of President Bashar al-Assad.
Australian Associated Press