Britain sanctions Russians linked to jailing of Putin critic Kara-Murza

FILE PHOTO: Russian opposition leader Vladimir Kara-Murza, vice chairman of Open Russia, testifies before a Senate Appropriations State, Foreign Operations and Related Programs Subcommittee hearing on "Civil Society Perspectives on Russia" on Capitol Hill in Washington, U.S., March 29, 2017. REUTERS/Joshua Roberts/File Photo

LONDON (Reuters) -Britain on Friday sanctioned a Russian judge and four others linked to the arrest and alleged poisonings of Kremlin critic Vladimir Kara-Murza who was jailed for 25 years this week for treason and other offences.

Russia branded the moves as illegal and former president Dmitry Medvedev reiterated a threat, frequently voiced by hardline nationalist Russian commentators, that Moscow's nuclear weapons could sink Britain into the sea.