LONDON (Reuters) – British finance minister Rishi Sunak called on more British companies on Sunday to wind down their existing investments in Russia and said new investments should be halted after President Vladimir Putin’s decision to invade Ukraine. “While I recognise it may be challenging to wind down existing investments, I believe there is no argument for new investment in the Russian economy,” Sunak said in a video message on Twitter. “I am urging asset owners and managers to think very carefully about any investment that would in any sense support Putin and his regime.” Several major Br…