By Kylie MacLellan and Maxim Rodionov LONDON/MOSCOW (Reuters) – Europe needs to diversify its energy supplies, the head of NATO said on Sunday, as Britain warned it was “highly likely” that Russia, the continent’s biggest natural gas supplier, was looking to invade Ukraine. Russia has massed some 120,000 troops near its neighbour and demanded the western defence alliance withdraw troops and weapons from eastern Europe and bar Ukraine, a former Soviet state, from ever joining the Western defence alliance. U.S. officials have said Russia’s military buildup has expanded to include supplies to tre…