ISTANBUL (Reuters) - A Turkish army helicopter was shot down by Syrian Kurdish YPG fighters near the north Syrian town of Afrin, President Tayyip Erdogan said on Saturday, and the Turkish military said two soldiers on board the aircraft were killed.

Turkish President Tayyip Erdogan greets his supporters during a meeting of the ruling AK Party in Corum, Turkey January 28, 2018. Yasin Bulbul/Presidential Palace/Handout via REUTERS

YPG sources separately confirmed the downing of the helicopter.

“One of our helicopters was downed just recently,” Erdogan told members of his AK Party in Istanbul. “These things will happen, we are in a war ... We might lose a helicopter, but they’ll pay the price for this.”

A statement from the Turkish military did not specify a reason for why the helicopter crashed. It said two soldiers on board were killed and technical crews were investigating the crash.

The downed helicopter was the first officially confirmed loss of a Turkish aircraft over Syria since the start of the country’s long-running civil war.

In another statement, the Turkish military said a total of nine soldiers were killed and 11 wounded on Saturday in clashes with mainly Kurdish forces near Afrin. It said it had killed 39 militants.

Ankara launched an air and ground offensive last month against Kurdish fighters in Syria’s Afrin region on its border, opening a new front in the multi-sided Syrian war.

Separately, the Turkish military said on Friday the construction of a fifth military post near Syria’s northwestern region of Idlib had begun.

Turkey agreed to set up 12 observation posts in Idlib and neighbouring provinces under a deal reached with Tehran and Moscow to try to reduce fighting between pro-government forces and mainly Islamist insurgents in northwest Syria.

However, the “de-escalation” in violence they were meant to monitor has collapsed. The Syrian army, alongside Iranian-backed militias and heavy Russian air power, launched a major offensive in December to take territory in Idlib province.

Idlib is one of the last main strongholds of rebels opposed to President Bashar al-Assad, who have been driven from most of their bastions in Syria since Russia joined the war on the side of Assad’s government in 2015. Turkey has long been one of the main allies of the anti-Assad rebels.