(CNN)Two Turkish troops were killed Saturday when their helicopter crashed in Afrin, Syria, near the Turkish border, Turkish state news agency Anadolu reported.
"One of the two Atak helicopters of ours operating on Afrin region unfortunately collapsed. Two brave members of armed forces martyred," Turkish Prime Minister Binali Yildirim said, according to Anadolu.
"There is no evidence that it was downed by an outside intervention," Yildirim said.
But Turkish President Recep Tayyip Erdogan said earlier Saturday the helicopter was downed as part of country's military action against US-backed Syrian Kurds in the area.
"A little while ago, one of our helicopters was downed," Erdogan said. "Maybe one of our helicopters is gone, but they will pay for this not in kind, but so much more."
The Turkish army confirmed the crash but did not comment on a cause.
An army statement said a team of investigators is carrying out a "technical investigation."
Turkey moves against Kurdish militia in Syria
Turkey began airstrikes against Syrian-Kurdish YPG militia in Afrin last month and later launched a ground operation.
Turkey said it launched the operation to target "terrorist organizations," including YPG forces.
Turkey has long fought Kurdish unrest in the southeastern part of the country. It's determined to prevent the establishment of a Kurdish state across the border in Syria and has used military force in the past against Kurds and ISIS in the northern part of the neighboring country.
But Turkey's operation in Afrin is raising tension between the United States and its NATO ally because Washington supports YPG fighters in the battle against ISIS in Syria.