Turkish warplanes and artillery hit a Syrian village held by Kurdish-led forces early on Saturday, a monitoring group and Kurdish sources said, as Turkey continued an offensive inside northern Syria.
The Syrian Observatory for Human Rights said that airstrikes and shelling hit the village of Tel al-Amarna, which had been captured days earlier by the Kurdish-led Democratic Forces of Syria (DFS). Reports of casualties could not immediately be verified.
"Turkey has been attacking our forces that are fighting against ISIS (Islamic State) groups," according to statement from the Jarabulus Military Council, which is allied with the DFS.
The area in question lies about 8 kilometres south of Jarabulus, a border town captured from Islamic State extremists on Thursday by Syrian rebels backed by Turkish tanks and airstrikes.
Turkey launched this week the Jarabulus operation, its first ground offensive inside Syria, against Islamic State and the dominant Kurdish Democratic Union Party (PYD), which it regards as the Syrian branch of Kurdish rebels operating on its soil.
The DFS, dominated by the PYD's armed wing, have enjoyed US backing as the main force on the ground inside Syria to have fought against Islamic State.
Islamic State has controlled territory along the Syrian border since 2013. In 2014, the Kurds, backed by US air power, began to push the group back, taking most of the border land.
After the Kurdish-led forces seized Minbij city, west of the Euphrates river, this month from Islamic State, the last major town on the border under the extremists' control was Jarabulus and a race developed between Turkey and the Kurds.
The US has said the Kurds should hold off and retreat over the Euphrates River to the west, and that it would not back them with air power if they moved on the town.
Turkey is a staunch backer of Syrian rebel groups fighting the government of President Bashar al-Assad and has moved hundreds of fighters into the Jarabulus region to fight Islamic State and the Kurds. Among the fighters are ethnic Turkmen brigades.
Syrian Turkmen leader Emin Bozoglan told Turkish media that the operation in Jarabulus is aimed at taking al-Bab, an Islamic State-held city near Aleppo, the main contested area of northern Syria in which nearly every side in the complex civil war is taking part.
The Kurds have also set their sights on al-Bab.
They aim to connect the main chunk of their territory in the north-east with Efrin, an enclave to the west, which is surrounded by rebels and Turkey, both of whom oppose Kurdish ambitions for self-administered regions.
In between the areas sit Minbij and al-Bab.
US Secretary of State John Kerry said late on Friday in Geneva that the US had supported Kurdish fighters on a "limited basis" and remained in close coordination with Turkey.
"We are for a united Syria. We do not support an independent Kurd initiative," Kerry said.
Meanwhile, while Turkey says it is focused on the west of the river, Kurds said Turkish forces had also crossed into Syria near Kobane, a symbolic town to the east of the Euphrates, and began constructing a wall.
"The aim is to impose a kind of an economic siege on the area," said Idriss Nassan, a senior Kurdish official in Kobane.