Ankara: Kurdish rebels raided a Turkish police station and fired on railway workers in two separate attacks that left five dead, officials said on Friday, amid renewed conflict between the security forces and insurgents that has wrecked a fragile peace process.

Violence has sharply increased in Turkey in the past week, with the government launching aerial strikes against Kurdistan Workers’ Party, or PKK, bases in northern Iraq, and the rebels escalating attacks against Turkey’s security forces. Some 20 people, most of them soldiers, have died in the renewed violence.

PKK militants raided the police station in the town of Pozanti, in southern Adana province, late on Thursday, killing two policemen and touching off a gunfight that also killed two rebels, said Governor Mustafa Buyuk. He said the rebels were armed with automatic rifles and hand grenades.

In the eastern province of Kars, the rebels detonated a bomb they placed on rail tracks and later fired on rail workers who were sent to repair the line, the region’s deputy governor, Adem Unal, told the state-run Anadolu Agency. One of the workers was killed.

Turkey last week conducted air assaults on Daesh targets and also opened its airbases for sorties by the US-led coalition fighting the group. The decision came after a suicide bombing blamed on Daesh killed 32 people and militants fired on Turkish troops, killing a soldier.

But Turkey shifted focus to the PKK following an attack claimed by the rebels that killed two policemen. That is complicating the US war on Daesh militants, which has relied heavily on Syrian Kurdish fighters affiliated with Turkey’s Kurdish rebels.

Turkish Prime Minister Ahmet Davutoglu has said Turkey’s onslaught against the PKK will continue until its fighters lay down arms, despite calls from Turkey’s main pro-Kurdish political party for the resumption of peace efforts. On Thursday, Davutoglu vowed renewed strikes against Daesh militants if the group attacks Turkish targets again.

“A single shot fired at our soldiers will result in the destruction of all those who fired the shot, until no one dares again to conduct such a thing at our border,” Davutoglu said. “These operations will continue until all arms are laid down and armed [fighters] leave the country, and until [Daesh] stops being a threat.”

The Kurdish party’s co-chairman renewed his plea for peace on Friday, as Turkey began holding funerals for the two officers killed in the police station attack and three soldiers who were slain in southeast Turkey on Thursday.

“The dialogue — slow as it was — must resume,” Selahattin Demirtas said in televised comments. “Fingers must be removed from the trigger.”

Kurdish activists and government critics say Turkey’s toughened stance against the PKK is a tactic aimed at strengthening the ruling party and attracting nationalist votes ahead of possible new elections in November. Davutoglu’s Justice and Development party lost its parliamentary majority in June and has until August 24 to form a coalition government, otherwise new elections will be called.

The PKK, considered a terror organisation by Turkey and its Western allies, launched its armed campaign for autonomy in Turkey’s southeast in 1984. The conflict has killed tens of thousands of people since then.

The Kurds declared a ceasefire in 2013 as part of the peace efforts, but halted a planned withdrawal of fighters from Turkish territory, accusing the government of not keeping promises.