(Reuters) – Energy supplier National Grid reported a 16% jump in annual pre-tax profit on Thursday, but said that rising energy prices and a cost-of-living crisis in Britain posed a “significant” challenge. The utility, which runs Britain’s energy systems, said underlying profit before tax from continuing operations rose to 3.06 billion pounds ($3.78 billion) in the year ended March 31, from 2.62 billion pounds a year earlier. ($1 = 0.8087 pounds) (Reporting by Shanima A in Bengaluru; Editing by Aditya Soni)