VLADIVOSTOK, Russia (Reuters) - Russian President Vladimir Putin said on Tuesday that the prosecution of former U.S. President Donald Trump was politically motivated and showed that the U.S. political system was "rotten".

In comments at a forum in Russia's Far Eastern city of Vladivostok, Putin also said that significant changes in the U.S.-Russia relationship were unlikely regardless of who becomes the next president of the United States.

Trump, the front-runner for the 2024 Republican presidential nomination, is facing a series of criminal cases in which he is charged, among other things, with trying to overturn his 2020 presidential election defeat by Joe Biden.

Putin said what was happening now in the United States demonstrated "all the rottenness of the American system" and the persecution of a political opponent for political reasons.

(Writing by Felix Light and Mark Trevelyan; Editing by Gareth Jones)