Poroshenko: 'Ukraine is a spiralling tragedy'
Diplomatic efforts to resolve the conflict in eastern Ukraine are continuing in Munich.
Talks in Moscow on Friday between President Putin, the German Chancellor Angela Merkel, and the French President Francois Hollande, ended with a commitment to try to revive a failed ceasefire but few details have emerged.
Russia is accused of arming pro-Russian separatists in eastern Ukraine - claims it denies.
Speaking to delegates at the Munich security talks, Ukraine's president Petro Poroshenko brandished six Russian passports - further evidence, he said, of Russia's involvement in the conflict.