ISTANBUL/SURUC, Turkey (REUTERS) - The war against the Islamic State in Iraq and Syria (ISIS) threatened on Tuesday to unravel the delicate peace in neighbouring Turkey after the Turkish air force bombed Kurdish fighters furious over Ankara's refusal to help protect their kin in Syria.
Turkey's banned PKK Kurdish militant group accused Ankara of violating a two-year-old cease-fire with the air strikes, on the eve of a deadline set by the group's jailed leader to salvage a peace process aimed at halting a three-decades-long insurgency.
At least 35 people were killed in riots last week when members of Turkey's 15-million-strong Kurdish minority rose up in anger at the government for refusing to help defend the Syrian border town of Kobane from an ISIS assault.
"For the first time in nearly two years, an air operation was carried out against our forces by the occupying Turkish Republic army," the PKK said.
"These attacks against two guerrilla bases at Daglica violated the ceasefire," the PKK said, referring to an area near the border with Iraq.
The unrest in Turkey raised serious concerns that a peace process between Turkey and its Kurds could be in danger of collapse, a new source of turmoil in a region consumed by Iraqi and Syrian civil wars and an international campaign against Islamic State fighters.
U.S. President Barack Obama, who ordered a bombing campaign against ISIS fighters that started in August, was to discuss the strategy on Tuesday with military leaders from 20 countries, including Turkey, Arab states and Western allies.
Washington has faced the difficult task of building a coalition to intervene in Syria and Iraq, two countries with complex multi-sided civil wars in which most of the nations of the Middle East have enemies and clients on the ground.
In particular, U.S. officials have expressed frustration at Turkey's refusal to help them fight against ISIS. Washington has said Turkey has agreed to let it strike from Turkish air base; Ankara says this is still under discussion.
NATO-member Turkey has refused to join the coalition unless it also confronts Syrian President Bashar al-Assad, a demand that Washington, which flies its air missions over Syria without objection from Assad, has so far rejected.
Meanwhile, ISIS fighters have been fighting their way into the mainly Kurdish Syrian border town of Kobane, where the United Nations says thousands could be massacred within full view of Turkish tanks that have done nothing to intervene.
The fate of Kobane could wreck efforts by the Turkish government to end the insurgency by PKK militants, a conflict that killed 40,000 people but largely ended with the start of a peace process in 2012.
The peace process with the Kurds is one of the main initiatives of President Tayyip Erdogan's decade in power, during which Turkey has enjoyed an economic boom underpinned by investor confidence in future stability.
The unrest shows the difficulty Turkey has had in designing a Syria policy. Turkey has already taken in some 1.2 million refugees from Syria's three-year civil war, including 200,000 Kurds who fled the area around Kobane in recent weeks.
Jailed PKK co-founder Abdullah Ocalan has said peace talks between his group and the Turkish state could come to an end by Wednesday. After visiting him in jail last week, Ocalan's brother Mehmet quoted him as saying: "We will wait until October 15 ... After that there will be nothing we can do."
A pro-Kurdish party leader read out a statement from Ocalan in parliament on Tuesday in which the PKK leader said Kurdish parties should work with the government to end street violence. "Otherwise we will open the way to provocations that could bring about a massacre," Ocalan said in the statement, which the party said he wrote last week.
There was no immediate comment from the military on the report that it bombed Kurdish positions, once a regular occurrence in southeast Turkey but something that had not taken place for two years. The PKK said the strikes took place on Monday, although some Turkish news reports said they happened on Sunday. There was no immediate explanation of the discrepancy.
Prime Minister Ahmet Davutoglu said the Turkish military had retaliated against a PKK attack in the border area. "Yesterday there was very serious harassing fire around the Daglica military outpost. Naturally it is impossible for us to tolerate this. Hence the Turkish armed forces took the necessary measures," he told a news conference, without referring specifically to air strikes.
Hurriyet newspaper said the air strikes caused "major damage" to the PKK. "F-16 and F-4 warplanes which took off from (bases in the southeastern provinces of) Diyarbakir and Malatya rained down bombs on PKK targets after they attacked a military outpost in the Daglica region," Hurriyet said.
The general staff said in a statement it had "opened fired immediately in retaliation in the strongest terms" after PKK attacks in the area, but did not mention air strikes.
The battle for Kobane has grinded on for nearly a month, with ISIS slowly advancing and now in control of much of the town. Kurdish fighters known as Popular Protection Units (YPG) want Turkey to allow them to bring arms across the border.
"There are fierce clashes, with no retreat or progress (by ISIS). Yesterday, (ISIS) detonated three suicide car bombs in eastern Kobane," said Ocalan Iso, deputy head of the Kobane defence council.
In the Turkish town of Suruc, 10 km from the Syrian frontier, a funeral for four female YPG fighters was being held. Hundreds at the cemetery chanted "Murderer Erdogan"in Turkish and also "long live YPG" in Kurdish.
Sehahmed, 42, at the cemetery to visit the grave of his son who was a YPG fighter and died only a few days ago, said if Turkey had intervened in Kobani, the town would have been saved.
"For days now they are just watching our people get killed. Obama is too late too. (ISIS) is now inside the city, they're on the streets. The air strikes won't work, it will only delay the inevitable. Its too late for us. Our poor people, we face one disaster after another."
The U.S.-led coalition has hit ISIS positions in and around the town but failed to halt the advance. At least six air strikes were heard from the Turkish side of the border on Tuesday. Gunfire and shelling were audible from the Turkish side, where Kurds, many with relatives fighting in Kobane, have maintained a vigil, watching the fighting from hillsides.
"I hear that people say (Islamic State) control the east and southeast but in fact they are scattered all across the city. That is why clashes are taking place pretty much everywhere,"Adil Selmo, 28, said on the Turkish side. His brother-in-law in Kobane had told him no weapons or ammunition had made it.
Kurds complain that hundreds of refugees were detained after crossing into Turkey, and that wounded fighters died at the frontier because Turkish border guards would not let them in.
"If they had received help, even up to one hour before their deaths, they could have lived," said Omar, 34, a Kurdish activist who brought three wounded fighters to the frontier last week and watched them die.
"Once the (Turkish) soldiers realised they were dead, they said, 'Now you can cross with the bodies.'I cannot forget that. It was total chaos, it was a catastrophe." Kurds in neighbouring Iraq, who are also fighting hard against ISIS, said they had sent ammunition to help their Syrian brethren in Kobane. Syrian Kurds said the shipment could not get to Kobane without Turkey opening a supply route.
In Iraq, Kurdish forces and government troops have rolled back some ISIS gains in the north of the country in recent weeks, but the fighters have advanced in the west, seizing territory in the Euphrates valley within striking distance of the capital Baghdad.
The United States used helicopter gunships against the militants last week for the first time to prevent what Washington described as a threat to Baghdad's airport.
The White House says it will not send U.S. forces back into ground combat in Iraq, where Obama withdrew all troops in 2011 after an eight-year occupation. U.S. commanders have spoken of increasing U.S. advice and support for Iraqi ground forces.