Up to five pro-Russian gunmen have been killed near the eastern Ukrainian city of Slovyansk according to the Ukrainian Interior Ministry after the Ukrainian army moved to demolish illegal checkpoints on its outskirts.

One checkpoint was abandoned to the north when five armoured personnel carriers arrived with what appeared to be well-armed and disciplined troops flying the Ukrainian flag, but the latest reports say when the troops left after demolishing the checkpoint, pro-Russian forces returned.

Three more checkpoints were reported to have been destroyed to the north-east, which is where the exchange of fire produced the casualties.

Rebel sources said two more pro-Russian fighters were killed on a road leading to the town of Svyatogorsk, which the Ukrainian army claimed to have recaptured on Wednesday.

Russian President Vladimir Putin issued a warning on Thursday that any use of Ukraine’s army in the east would be a “very serious crime” and have “consequences”.