Turkey has angrily rejected international criticism of its attack on a Kurdish militia in Syria, reporting progress by its forces on the second day of an operation that world powers fear could further destabilise a region in turmoil.
Taking aim at the European Union and Arab powers Saudi Arabia and Egypt, which have voiced opposition to the operation, Turkish President Tayip Erdogan said those objecting to Turkey's actions were "not honest".
He threatened to permit Syrian refugees in Turkey to move to Europe if EU countries described his forces' move as an occupation.
"They are not honest, they just make up words," Erdogan said, singling out Saudi Arabia and Egypt.
"We, however, take action and that is the difference between us," he told officials from his ruling AK Party in Ankara.
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 intensify the conflict, and runs the risk of Islamic State prisoners escaping from camps amid the chaos.
Turkey's operation began days after a pullback by US forces from the border, and senior members of US President Donald Trump's own Republican Party have condemned him for making way for the incursion and abandoning Syrian Kurds, loyal allies of Washington in the fight against Islamic State in Syria.
"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 said later.
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.
There was no immediate comment on the situation in the prisons from Turkey.
CNN Turk broadcast video showing a crane overnight removing a concrete block from the border wall and commandos moving in single-file alongside the barrier.
In the Turkish border town of Akcakale, around 30 vehicles carrying Syrian rebels, many pick-up trucks mounted with anti-aircraft guns drove along the main road on the Turkish side of the border from Syria's Tel Abyad, a Reuters journalist said.
President Trump called the Turkish assault a "bad idea" and said he did not endorse it.
The United Nations Security Council will meet later on Thursday to discuss Syria at the request of the five European members, Britain, France, Germany, Belgium and Poland.
In a letter to the 15-member Council, Turkey said its military operation would be "proportionate, measured and responsible".
The 22-member Arab League also said it would hold an emergency meeting on Saturday.
Russia said it planned to push for dialogue between the Syrian and Turkish governments following the incursion.
Italy condemned the offensive as "unacceptable", saying military action in the past always led to terrorism.