MOSCOW, April 19 (Reuters) – A temporary nationalisation of Russian aluminium giant Rusal is one of the options for helping the company which was hit by the U.S. sanctions, a Kremlin spokesman said on Thursday. He was commenting on a proposal set out by Alexander Shokhin, a former deputy prime minister, for the state to buy out shares of affected companies as a way of helping them to mitigate the negative effect of sanctions.