Three Russian tanks and other military vehicles crossed the border into Ukraine on Thursday, prompting a skirmish between Ukrainian and Russian forces, acting Ukrainian Interior Minister Arsen Avakov said.

The Russian Foreign Ministry told the BBC that the claim was “another fake piece of information.”

According to Avakov, tanks crossed the border at a checkpoint controlled by pro-Russian separatists in the Luhansk region of eastern Ukraine. Armored vehicles and artillery were part of the columns, Avakov said, citing Ukrainian intelligence.

Two of the tanks split off and headed in the direction of Gorlovka, also known as Horlivka, and were attacked by Ukrainian military forces, Avakov said.

Part of that column was destroyed, he said.

Also on Thursday, Ukrainian President Petro Poroshenko and Russian President Vladimir Putin “held a substantial and long phone conversation,” the Ukrainian President’s media office said, but it was unclear if that conversation occurred before or after the reported tank incursion.

The leaders discussed Poroshenko’s peace plan to resolve the situation in the east of Ukraine, the media office said.