By Sam Tobin LONDON (Reuters) – A prominent Russian businessman on Tuesday asked a London court to pause an $850 million fraud lawsuit brought by two Russian banks because of UK sanctions, arguing that any money recovered could be used to “indirectly fund the war in Ukraine”. Boris Mints and his sons Dmitry, Alexander and Igor are being sued by National Bank Trust, which is 99% owned by the Central Bank of Russia, on behalf of Bank Otkritie, once Russia’s largest private lender before it collapsed in 2017. Lawyers representing the Mints family – who deny the banks’ fraud allegations – say the …