Twenty-two US soldiers were injured in a helicopter accident in northeastern Syria, according to what the Central Command of the US Army "Centcom" announced on Tuesday, without mentioning its circumstances.

"On June 11, an accident involving a helicopter in northeastern Syria injured 22 American soldiers to varying degrees," Centcom said in a statement.

Ten of the injured were transferred outside the central command's area of operations to receive care in advanced health facilities, according to the statement.

"The cause of the accident is still under investigation, although no hostile fire has been reported," Centcom said.

It is rare to announce similar incidents in Syria, where the international coalition forces, most notably the US forces, are deployed in the areas of influence of the Kurdish forces and their allies in northeastern and eastern Syria. American forces are also present at the al-Tanf base in the south, near the Jordanian and Iraqi borders.

US bases have been repeatedly targeted during the past year, with cells affiliated with the Islamic State standing behind some of them, while others point fingers at armed groups loyal to Tehran.

Since 2011, Syria has been witnessing a bloody conflict with many sides, which, since its outbreak in 2011, has caused the death of more than half a million people, massive destruction of infrastructure, and the displacement of more than half of the population inside and outside the country.