Some European traders have started to pay Russia for gas sales in rubles, while large clients have yet to do so, two sources familiar with the matter told Reuters on Thursday. “Several traders, maybe more than five, have started payments,” one source said on condition of anonymity because they were not authorised to speak to the media. Russian President Vladimir Putin has demanded that countries he terms “unfriendly” must pay for gas in rubles or be cut off. Under the new Russian payment system, buyers are obliged to deposit euros or dollars into an account at Gazprombank, which has then to co…