ANKARA (Reuters) - Turkey’s army said it clashed with Islamic State over the border in Syria, leaving one soldier and 23 militants dead, as Ankara stepped up an operation to clear insurgents from the frontier region.

Three other Turkish soldiers were wounded in the battle near the Syrian village of Ziyara over the past 24 hours, part of Ankara’s “Euphrates Shield” offensive, the military added on Wednesday.

A Syrian rebel commander taking part in the “Euphrates Shield” operation told Reuters that Islamic State had fought furiously during a battle for the village of Turkman Bareh, which was captured by rebels this week.

The commander said Islamic State had drafted in reinforcements to the area, not far from Dabiq, a village with symbolic importance to the militants since it is cited in the Koran as the scene of an apocalyptic battle.

“We expect resistance in the remaining villages,” the commander said.

Turkey’s entry into Syria has raised concerns of a further escalation in an increasingly fraught regional conflict.

Ankara says its efforts to cleanse its border region of Islamic State militants are legitimate under international law as self-defense after months of rocket attacks and bombings in cities along the boundary.

President Tayyip Erdogan has also made it clear that Turkish forces are in Syria to prevent the Syrian Kurdish militia, which is backed by the United States to fight Islamic State, from expanding areas under its control.

Two Syrian rebel fighters backed by Turkey died in other clashes with Islamic State along the boundary, the Turkish military statement said. The Ankara-backed rebels had seized control of around 980 square km (378 square miles) of territory since Euphrates Shield began on Aug. 24, it added.

Separately, U.S.-led coalition warplanes carried out nine air strikes on Islamic State targets in northern Syria, killing five further militants, the military said in its daily summary of the Syrian operation.