Kurdish militants killed two Turkish soldiers in a roadside bombing on Sunday, the military said, apparently retaliating for Ankara's crackdown on the Kurdistan Workers Party (PKK) launched in tandem with strikes on Islamic State insurgents in Syria.
Long a reluctant member of the US-led coalition against Islamic State, Turkey made a dramatic turnaround this week by granting the alliance access to its air bases and launching air raids against both the jihadist movement and the PKK.
But the relapse into serious conflict between Turkey and the PKK has raised doubts about the future of NATO member Turkey's peace process with Kurdish foes that started in 2012, after 28 years of bloodshed, but has recently stalled.
A car bomb and roadside explosives hit a passing military vehicle on a highway near Diyarbakir in the mainly Kurdish southeast of Turkey overnight on Sunday, an army said. Kurdish militants then opened fire on the vehicle with rifle fire, it said. Four other soldiers were wounded.
At least six people had been detained in connection with the attack, Dogan news agency reported.
The PKK, which Ankara and Washington deem a terrorist group, has also targeted police officers in the southeast and elsewhere, accusing the Islamist-rooted central government of covertly helping Islamic State to the detriment of Syrian Kurds.
The outlawed PKK has waged an insurgency against Ankara for Kurdish autonomy since 1984. Opposition politicians and critics accuse President Tayyip Erdogan of taking up the campaign against Islamic State as political cover to clamp down on Kurds.
Prime Minister Ahmet Davutoglu, who has said the operations will continue as long as Turkey faces a threat, discussed security with U.N. Secretary-General Ban Ki-moon in a telephone call overnight.
NATO said ambassadors will meet on Tuesday to discuss security at Turkey's request.
US DENIES CONNECTION
A senior U.S. diplomat condemned recent PKK attacks but said there was no link between Turkey's new strikes on Kurdish militants and its newfound boldness in tackling Islamic State, which has seized large expanses of neighbouring Syria and Iraq.
"There is no connection between these air strikes against PKK and recent understandings to intensify U.S.-Turkey cooperation against ISIL," Brett McGurk, the deputy special presidential envoy for the coalition to counter Islamic State, said on Twitter, using one of Islamic State's acronyms.
White House spokesman Ben Rhodes, on an official visit to Kenya with President Barack Obama, told a news conference in Nairobi: "The U.S. of course recognises the PKK specifically as a terrorist organization. And so, again, Turkey has a right to take action related to terrorist targets. And we certainly appreciate their interest in accelerating efforts against ISIL."
Turkey said on Saturday its decision to enter the battle against Islamic State, soon after an IS suicide bomber killed 32 people, mainly Kurds, in the Turkish town of Suruc, would help create "a safe zone" across the nearby border in northern Syria.
Members of the Turkish opposition say they are concerned Erdogan aims with new attacks on the PKK to whip up anti-Kurdish sentiment ahead of a possible early election later this year.
The Islamist-based AK Party he founded has until late August to find a junior coalition partner or face an early election.
The AKP lost its single-party majority for the first time in more than a decade in June, in part due to the success of the pro-Kurdish Peoples' Democratic Party (HDP), which entered parliament for the first time.
"One of the aims of the air, land and media operations carried out right now is to undermine the HDP in early elections," HDP head Selahattin Demirtas said on Twitter.