DIYARBAKIR, Turkey (Reuters) - Turkish warplanes bombed Kurdish insurgent targets overnight after the militants staged what appeared to be their deadliest attack since the collapse of a two-year-old ceasefire in July and killed 16 government soldiers.
The military said its aircraft bombed 23 targets in a mountainous area near the Iraqi frontier on Monday. Another six soldiers had been wounded, but none were in critical condition.
The clashes, weeks before polls the ruling AK Party hopes will restore its majority, threaten to sink a peace process President Tayyip Erdogan launched in 2012 in an attempt to end an insurgency that has killed more than 40,000 people.
Kurdistan Workers Party (PKK) rebels said they had killed 31 servicemen in an attack on a convoy and clashes on Sunday in the mountainous Daglica area of Hakkari province, near the Iraqi border. The army statement said 16 had died, making this the highest military death toll in a single attack for years.
"Those mountains will be cleared of these terrorists. Whatever it takes, they will be cleared," Prime Minister Ahmet Davutoglu told a news conference after a meeting with the chief of the military general staff.
"The mountains, plains and cities of this country will not be left to terrorists. That's it. Our sorrow is deep and grave."
The PKK is designated a terrorist organization by Turkey, the European Union and United States.
Erdogan said in an interview late on Sunday on the A Haber TV channel that the fight against the PKK would now become more determined. He said 2,000 PKK militants had been killed since the conflict resumed in July.
Uncertainty arising from the conflict, coinciding with a campaign against Islamic State militants based in Syria, has unnerved investors, with the lira dropping to record lows against the dollar.
The unrest has raised questions over how security can be guaranteed for the Nov. 1 vote. But Erdogan, who has dominated Turkish politics for over a decade and now seeks a parliamentary mandate to extend his executive powers, said the election would go ahead.
The pro-Kurdish Peoples' Democratic Party (HDP), accused by the government of being bound to the PKK, called for a renewed ceasefire and an extraordinary parliamentary meeting. Leader Selahattin Demirtas cut short a European visit, saying there could be no justification for killing.
"We will not surrender to war policies which only deem death proper for the people's poor children and splatter blood on the mothers' dreams of peace," he wrote on Twitter, referring to the Daglica attack and conflict in the southeastern town of Cizre.
Local media reports said a lieutenant colonel in command of the Daglica battalion was among those killed.
"Two of our armored vehicles suffered heavy damage after the detonation of hand-made explosives on the road. As a result of the blast, there were martyrs and wounded among our heroic armed comrades," the military statement said.
A security source said that after the militants detonated explosives along the road, a clash broke out between the soldiers and fighters from the PKK.
Davutoglu chaired an emergency meeting with military and intelligence chiefs on Sunday night in Ankara following the attack, cutting short a visit to the city of Konya.
"The pain of our security forces who were martyred in the treacherous attack by the separatist terrorist organization sears our hearts," Erdogan said in a statement.
After he spoke, some 200 people chanting pro-Erdogan slogans attacked the Hurriyet newspaper's offices in Istanbul, accusing it of misquoting him and implying that the president was trying to gain political capital from the Daglica attack.
Protesters with sticks and stones smashed windows, according to the Dogan news agency, part of the same group as Hurriyet, which has attracted criticism from pro-government circles over its coverage of the conflict.
The PKK launched its insurgency in 1984 with the aim of carving out a state in the mainly Kurdish southeast. It later moderated its goal to strengthening Kurdish political rights.
Some Turks fear Kurds in Syria, backed by the United States in their fight against Islamic state, and Kurds in Iraq, as well as the PKK, harbor ambitions of an independent contiguous Kurdish state.
Writing by Daren Butler; Editing by Nick Tattersall and Ralph Boulton