SOFIA (Reuters) - Poland's president said on Tuesday Warsaw would join any international moves to step up sanctions on Russia, after Moscow opened fire on and seized three Ukrainian navy ships near Russian-annexed Crimea over the weekend.

The U.S. State Department, the European Union, Britain, France, Denmark, and Canada have all condemned what they called Russian aggression. Moscow accuses the Ukrainian vessels of intruding into its territorial waters on Sunday, which Kiev denies.

"If there are such international initiatives, like further sanctions (on Russia), Poland will take part in these initiatives, because we are ready for all actions that will lead to solving the conflict," Polish President Andrzej Duda said during a visit to Bulgaria, speaking through a Bulgarian translator.

ADVERTISEMENT