Five Kurdish insurgents were killed in a clash with Turkish forces in the eastern Agri province on Saturday, the military said, after it sent in extra troops and armed helicopters against the militants.

Turkey called in the back-up force, including reconnaissance planes, after insurgents from the Kurdish Workers Party (PKK) opened fire and wounded four soldiers in the Diyadin district of Agri near the Iranian border, the military said.

The government said PKK militants were trying to destabilise the country before a parliamentary election in June.

“Terrorists with rifles opened fire on our forces, who immediately returned fire,” the military said. “We have sent reconnaissance planes, armed helicopters and additional ground troops to the region and the clash is still ongoing.”

No one from the PKK was immediately available for comment.

Ankara and the PKK agreed to a ceasefire two years ago, as part of negotiations to end a three-decade insurgency that has killed 40,000 people. But the fragile peace process has been strained ahead of the election.

Turkish president Tayyip Erdoğan accused pro-Kurdish politicians of using insurgency as a campaign tactic.

“Twenty-five terrorists are engaged in clashes right now against our soldiers,” he was quoted as saying by the state-run Anatolian news agency.

“A certain political party is trying to gain votes through the actions of this divisive terrorist organisation,” he said in an apparent reference to the pro-Kurdish HDP political party.

Erdoğan has invested significant political capital in the peace process that started in 2012 and his authority, to some extent, is linked to its success.

A sweeping majority for the AK party he founded would allow it to change the constitution and give Erdoğan the broader presidential power he seeks.

Erdoğan and the AK party remain popular among many of Turkey’s roughly 16 million Kurds, particularly those who distrust the PKK and appreciate Erdoğan’s efforts to seal a peace deal.

Deputy prime minister Yalçın Akdoğan, a government negotiator in the peace talks, said the attacks were aimed at causing instability ahead of the election.

“Attempts against public order, election safety and the peace of the nation cannot be tolerated,” he said on Twitter. “To put hopes on guns in an election is a sign of desperation and disrespect of the national will.”

Last month, Turkish forces exchanged fire with Kurdish rebels in the south-east, the Turkish military said, just days after jailed PKK leader Abdullah Öcalan said the group’s insurgency had become “unsustainable”.