SINGAPORE, March 27 (Reuters) - Spot uranium prices rose $4 to $95 a lb on Tuesday, their highest since the late 1970s, said UxC, a provider of uranium prices. Uranium, used to fuel most of the world's nuclear reactors, was trading at $36.25 at the start of 2006 and ended the year around $60 <UX-U3O8-SPT>, latest UxC data showed. Prices have soared 10-fold from 2002 after years of under-investment, while demand from utility companies embarking on new reactor programmes has jumped as governments around the world look for ways to limit carbon emissions from fossil fuels.