President Petro Poroshenko on Friday called it a "moral duty" to punish those responsible for downing the MH17 flight over Ukraine one year ago, killing  all 298 people on board.

"Our moral duty to honour the memory of the fallen ones is to ensure a fair punishment for those guilty in downing the aircraft. This crime represents a threat to the whole international community," Poroshenko said in a statement published on the presidential website. "The murderers should know that... punishment is inevitable."