Kurdish militants claimed responsibility for the assassination on Wednesday of two Turkish police officers in what they said was retaliation for a suspected Islamic State suicide bombing which killed 32 people, mostly young students.
The Kurdistan Workers Party (PKK) said in a statement on one of its websites that the two police officers were killed at around 6am in the southeastern town of Ceylanpinar for “collaboration with the Daesh [Islamic State] gangs”.
Security sources earlier told Reuters the officers were found dead with bullet wounds to the head in a house they shared in Ceylanpinar, on the border with Syria some 160km east of Suruc, the site of Monday's suicide bombing.
Many of Turkey's Kurds and opposition supporters suspect President Tayyip Erdogan and the ruling AK Party of covertly backing Islamic State against Kurdish fighters in Syria, something the government has repeatedly denied.
Anti-government protests after Monday’s bombing in Suruc erupted in several cities for a second night on Tuesday, with some of the demonstrators chanting “Murderer Islamic State, collaborator Erdogan and AKP”.
“Although Islamic State has been held responsible for this attack, Turkey’s AKP government, by resisting the taking of effective measures to prevent Islamic State and other reactionary forces, bears the real responsibility,” the opposition Peoples’ Democratic Party (HDP), whose support base is mostly Kurdish, said in a statement.
Turkey's Nato allies have expressed concern about control of its border with Syria which in parts runs directly parallel with territory controlled by Islamic State. The prospect of conflict spilling on to Turkish soil, embroiling Kurds, Islamist militants and security forces, will raise alarm inside and outside Turkey.
On Tuesday prime minister Ahmet Davutoglu rejected accusations that Turkey had tacitly supported Islamic State and had unwittingly opened the door to the bombing; but he said initial evidence suggested the Islamist radical group was responsible.
A senior Turkish official told Reuters there was “strong evidence” to suggest the bomber was a 20-year-old man born in the southeastern province of Adiyaman and of Kurdish origin, who had travelled to Syria last year with the help of a group linked to Islamic State.
“He was active in a Syria-linked group supporting the Islamic State. We know that he went to Syria illegally. It was not possible to track him during his time there,” the official said, speaking on condition of anonymity because of the sensitivity of the investigation.
The official said the suspect had links with another alleged bomber who attacked an HDP rally in the mostly Kurdish southeastern city of Diyarbakir days ahead of a June 7th parliamentary election, killing four people and wounding at least 200.
The Radikal newspaper quoted what it said was the man's mother saying he was a former student at Adiyaman university who had worked as a painter with his 25-year old brother before going abroad.
“I don’t know what they were doing abroad, they never said. They were just telling me they were fine,” Semure Alagoz told the newspaper. “I don’t know where he is now. I don’t know if they joined ISIL, if they went for jihad. They are both good kids, they wouldn’t harm anyone.”
Two lawmakers from the HDP submitted separate parliamentary motions on Wednesday naming a 20-year-old woman as a suspect, and asking why police had released her from custody last month.
The turmoil comes at a difficult time for Turkey, with a caretaker government in charge while the AKP seeks a junior coalition partner after losing its majority in the June election for the first time in more than a decade.
At least 51 people have been arrested in protests in Istanbul alone, and police seized more than 200 petrol bombs and a rifle, the governor's office in Turkey's biggest city said.
There were also protests overnight in the capital Ankara, where demonstrators carried pictures of those killed in the Suruc attack, as well as banners of the youth federation of which many of the victims were members.
Anti-government groups have vowed further demonstrations and the HDP has called for supporters to converge in Istanbul for a mass rally this weekend.
The prospect of further unrest has unnerved investors already worried by the uncertain political outlook. The lira was the worst performer among major emerging market currencies on Wednesday, falling more than 1 per cent against the dollar.