By Tsvetelia Tsolova and Anna Koper SOFIA/WARSAW (Reuters) -Russia’s Gazprom halted gas supplies to Poland and Bulgaria on Wednesday over their refusal to pay in roubles, cranking up an economic war with Europe in response to Western sanctions imposed for Moscow’s invasion of Ukraine. The state-controlled pipeline monopoly, which supplies Europe with about 40% of its gas needs, said transit via Poland and Bulgaria – whose pipelines supply Germany, Hungary and Serbia – would be cut if fuel was siphoned off illegally. Fears more states could be hit, in particular Germany, Europe’s industrial pow…