That was followed late in the evening by the beginning of a ground operation, the Turkish defence ministry said. The spokesman for one of the pro-Turkish Syrian militant groups told AFP the land phase of the operation began in Tal Abad, and Turkish media reported special forces and armoured vehicles had entered at several points along the border. At least eight civilians and seven Kurdish fighters were killed on Wednesday, mostly in cross-border artillery fire, in various locations along the border, including in the city of Qamishli, a war monitor said.

The assault had seemed inevitable since US President Donald Trump on Sunday announced a military pullback from the border, but the attack triggered international condemnation and an emergency meeting of the UN Security Council set for Thursday.

The White House said Wednesday the Turkish assault was a "bad idea" even after it had effectively gifted Erdogan a green light and smashed the US alliance with the Kurdish forces, who spearheaded five years of ground battles against the Islamic State group in Syria.

Kurdish sources reported that at least 16 positions were struck in the first hours of the operation, to which the Kurdish-led Syrian Democratic Forces (SDF) responded with some cross-border artillery fire.

The SDF called on the international community to impose a no-fly zone to protect against "an imminent humanitarian crisis". Erdogan, who dubbed the attack "Operation Peace Spring", says the offensive is necessary to curb the power of the SDF due to its ties with Kurdish insurgents inside Turkey.

Copyright Agence France-Presse, 2019