By Maria Tsvetkova and Aleksandar Vasovic KYIV (Reuters) – Western allies announced sweeping new sanctions against Moscow on Saturday, including kicking key Russian banks off the main global payments system, as a defiant President Volodymyr Zelenskiy said Ukrainian forces were repelling Russian troops advancing on Kyiv. Seeking to ratchet up economic punishment for Russian President Vladimir Putin over his invasion of Ukraine, the United States and its European partners also said they would impose restrictions on Russia’s central bank to limit its ability to support the rouble and finance his …