This shift could prove lasting, as India is the world's number three importer of oil and Russia became its leading supplier after Europe shunned Moscow's supplies following its invasion of Ukraine begun in February last year. After a coalition opposed to the war imposed an oil price cap on Russia on Dec. 5, Indian customers have paid for most Russian oil in non-dollar currencies, including the United Arab Emirates dirham and more recently the Russian rouble, multiple oil trading and banking sources said.