MOSCOW

Russia on Thursday again accused Ukraine of downing a Russian military plane en route for a prisoner swap, branding it "a monstrous act."

"Ukrainians killed their citizens, who were supposed to be home within a day, this is a monstrous act," Kremlin spokesman Dmitry Peskov told reporters at a press briefing in Moscow.

He agreed that an international investigation is necessary to clarify what caused the Wednesday crash of the Il-76 military plane in Belgorod, Russia, near Ukraine’s border, which killed all 74 people on board.

Asked about the prospects for further prisoner exchanges between Russia and Ukraine, he said: “No one knows how the catastrophe will affect it."

Russia’s Defense Ministry on Wednesday accused Ukraine of shooting down a plane carrying captured Ukrainian servicemen for a prisoner exchange.

There were 65 captured Ukrainian armed forces servicemen on board, six crew members of the aircraft, and three escorts. The crew and all the passengers on the plane were killed, it said, calling what happened "a terrorist attack" mounted in order to accuse Russia of killing Ukrainian servicemen.

Ukrainian authorities were "well aware of the planned transportation" in advance, the ministry stressed.