Russia cut gas exports to Europe by 60 per cent today, plunging the continent into an energy crisis 'within hours' as a dispute with Ukraine escalated. This morning, gas companies in Ukraine said that Russia had completely cut off their supply.Six countries reported a complete shut-off of Russian gas shipped via Ukraine today, in a sharp escalation of a struggle over energy that threatens Europe as winter sets in.Bulgaria, Greece, Macedonia, Romania, Croatia and Turkey all reported a halt in gas shipments from Russia through Ukraine. Croatia said it was temporarily reducing supplies to industrial customers while Bulgaria said it had enough gas for only 'for a few days' and was in a 'crisis situation'.