(Reuters) – Russia’s Rosneft offered oil products from its refineries for loading May-June in a tender requiring pre-payment in roubles, three market sources told Reuters on Tuesday. Last week Rosneft has offered 6.5 million tonnes of crude oil via tenders for loading in May-June, seeking full pre-payment in roubles for the first time. Bids were invited for about 2 million tonnes of fuel oil and vacuum gasoil (VGO), 1.4 million tonnes of naphtha and 1 million tonnes of marine diesel oil (MDO), traders added. (Reporting by Reuters; Editing by David Goodman)