An umbilical for use in the offshore production of hydrocarbons, the umbilical comprising a plurality of functional elements contained within an outer sheath, at least one of said functional elements comprising a multicore electric cable, said multicore electric cable comprising a plurality of insulated electric conductors electrically insulated from each other and assembled together in a helical or S/Z manner, said multicore electric cable further comprising a protective polymer sheath surrounding said plurality of insulated electric conductors, said multicore electric cable further comprising a tubular metallic layer located inside said protective polymer sheath and surrounding said plurality of insulated electric conductors.