Turkish warplanes bombed Kurdish insurgent targets yesterday after 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 yesterday. Another six soldiers had been wounded, but none were in critical condition.

The clashes, weeks before polls the 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 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 meeting with the chief of military staff.

The mountains, plains and cities of this country will not be left to terrorists

“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 organisation by Turkey, the European Union and United States.

Erdogan said in an interview late on Sunday that the fight against the PKK would now become more determined. The unrest has raised questions over how security can be guaranteed for the November 1 vote. But Erdogan, who has dominated Turkish politics for over a decade and seeks a parliamentary mandate to extend his executive powers, said the election would go ahead. The pro-Kurdish Peoples’ Democratic Party (HDP), accused of being bound to the PKK, called for a renewed ceasefire and an extraordinary parliamentary meeting.

Demonstrators, wearing commando berets and holding pictures of the late Turkish army members who were killed by Kurdish militants, shout nationalist slogans during a protest against recent attacks on Turkish soldiers, in Istanbul, Turkey, yesterday.

Leader Selahattin Demirtas cut short a European visit, saying there could be no justification for killing.

“Two of our armoured 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,” a 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 organisation sears our hearts,” Erdogan said in a statement.

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, harbour ambitions of an independent contiguous Kurdish state.