Pro-Russian separatist rebels in eastern Ukraine will hold their own elections in October, the leader of the self-proclaimed Donetsk People’s Republic said Thursday. The announcement drew a rebuke from Ukrainian President Petro Poroshenko, who said any election that did not occur with oversight from Kiev could violate last February’s Minsk peace accord.

Slated for October 18, the elections will occur “on the basis of Ukrainian law … in the parts where it does not contradict the constitution and law” established in separatist-held eastern Ukraine, said Alexander Zakharchenko, self-styled prime minister of the Donetsk People’s Republic in eastern Ukraine, according to Agence France-Presse. Zakharchenko did not provide further details on how the elections would occur or whether rebels would be in contact with the Ukrainian government in Kiev.

The topic of elections was included in last February’s cease-fire deal between the Ukrainian government and pro-Russian separatists. Brokered by France and Germany, the agreement called for both sides to cease open warfare in eastern Ukraine and to remove heavy weaponry from the conflict’s front lines.

The deal also granted semi-autonomy to rebel-held territory in eastern Ukraine, under the condition that Kiev would run any future elections that occurred in the region. Rebel leaders would be allowed to pursue closer ties with Russia, but separatist regions would remain part of Ukraine, AFP noted in March. A previous round of rebel elections, held in November 2014 at the height of the conflict, drew condemnations from Kiev and the United States, Reuters reported.

Despite the ceasefire, sporadic clashes between Ukrainian government forces and separatist rebels have continued since February. More than 6,400 people have been killed in the eastern Ukraine conflict.

Western nations have joined Ukraine in repeated accusations that Russia has provided direct military support to the separatists. The Kremlin has denied any involvement. Poroshenko said an attempt to hold rebel elections without oversight from Kiev would be evidence of a Russian attempt to undermine the Minsk deal.

“I believe that attempts to conduct illegal elections that do not correspond to Ukrainian laws … will amount to a harsh Russian attack on Minsk II,” Poroshenko said, according to AFP. “I am certain that this would be irresponsible and would have ruinous consequences on attempts to de-escalate the situation in individual [rebel] districts” in eastern Ukraine, he added.