BEIRUT: The toll in Turkish air raids on Kurdish positions in northeastern Syria rose to 28 killed, a monitor said Wednesday, a day after Ankara said it had targeted "terrorist havens" near its border.
The Syrian Observatory for Human Rights said most of those killed were members of the Kurdish People's Protection Units (YPG), which is battling the Islamic State group in northern Syria.
Observatory director Rami Abdel Rahman said 19 others were wounded in the Tuesday raids on a media centre and other buildings in Al-Malikiyah, a town in Hasakeh province.
Abdel Rahman said a female Kurdish fighter was among the dead.
The YPG gave its own toll on Tuesday of 20 fighters killed and 18 wounded.
The US State Department said it was "deeply concerned" that the strikes were conducted "without proper coordination either with the United States or the broader global coalition" that is fighting IS in Syria and neighbouring Iraq.
Turkey, which backs Syrian rebel groups and which launched a ground operation in northern Syria last year, vowed to continue acting against groups it links to the outlawed Kurdistan Workers' Party (PKK).
It also killed six Kurdish peshmerga fighters in northern Iraq on Tuesday in an apparent accident.
Syria's foreign ministry on Wednesday condemned the air strikes, describing them as "a flagrant aggression by (President Recep Tayyip) Erdogan's regime on Syrian territory".
Once allied, Damascus and Ankara have become bitter adversaries since the eruption of Syria's conflict in 2011, which saw Turkey side with anti-government rebels.
And while Turkey's government sees the YPG as "terrorists," the Syrian regime has maintained cool ties with them, mostly in parts of northeast Syria where they share territory.
Turkey's strikes have underlined the complexities of the battlefields in Iraq and Syria, where twin US-backed offensives are seeking to dislodge IS from its last major urban strongholds.
They could also exacerbate tensions between Ankara and its NATO ally Washington, which sees the Kurds as instrumental in the fight against IS.
The US-backed Syrian Democratic Forces -- which are dominated by the YPG -- are waging a five-month-old offensive for IS's Syria stronghold Raqa.
The SDF accused Turkey of carrying out the strikes "to obstruct the progress of our campaign for Raqa".
"We call on the international community to intervene to put an end to these ongoing attacks on our territory," the SDF said in a statement published late Tuesday.