By Kate Abnett and Francesco Guarascio BRUSSELS (Reuters) – The European Commission on Thursday warned buyers of Russian gas they could breach sanctions if they converted gas payments into roubles, as officials struggled to clarify the EU’s stance on Moscow’s payments scheme, which has sowed confusion in the bloc. Russian gas giant Gazprom cut supplies to Poland and Bulgaria on Wednesday after they refused to pay for gas in roubles, marking Moscow’s toughest response yet to sanctions imposed by the West over the conflict in Ukraine. The escalation follows a decree issued by Russian President V…