ANKARA - The toll in Turkish air raids on Kurdish positions in northeastern Syria rose to 28 killed, a monitor said Wednesday, as Ankara said it had informed the United States and Russia before launching strikes against 'terrorist havens' in Syria and Iraq.
The US State Department had 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 the Islamic State group in both countries.
The Syrian Observatory for Human Rights said most of those killed were members of the Kurdish People's Protection Units (YPG), which is battling IS 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.
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.
Turkish Foreign Minister Mevlut Cavusoglu said: "Two hours before this operation, we shared information with the US and Russia that we would undertake an operation" in the region.
He said Ankara had told Washington in the "last few weeks" that it would undertake military operations but did not give further detail.
"Turkey acts transparently on all issues. We have no secret agenda... We respect Syria and Iraq's territorial integrity," he told reporters in Uzbekistan.
Cavusoglu said Ankara had "a legitimate right with these interventions" because of the threats to Turkey from these areas and urged its allies to support the efforts.
"There are terrorists that enter Turkey via different paths," he said.
Turkey says fighters of the YPG in Syria are linked to PKK separatists inside Turkey, who have waged an insurgency since 1984 that has killed over 40,000 people.
But Washington sees the YPG as essential in the fight against the Islamic State group (IS) in Syria.
The militia has captured chunks of territory in northern Syria but Ankara has repeatedly said it will not allow a "terror corridor" on its border.
Cavusoglu claimed that the US, whose commandos are working with local Kurdish forces in Syria, was fully aware the fighters are linked to the PKK.
The PKK is listed as a "terrorist group" by the US, the European Union and Turkey, but only Turkey sees the YPG as a terror outfit.
Washington is hoping the SDF, a Syrian Arab-Kurdish alliance dominated by the YPG, will push into the IS bastion of Raqa in Syria, but is wary of upsetting Turkey, a key NATO ally.