Greek Prime Minister Alexis Tsipras demanded the resignation of the country's top tax official on Friday, a day after she was charged with breach of duty in attempting to defer tax collections from the country's TV stations by a year, government officials said. Katerina Savvaidou, who as the general secretary for state revenues, holds a key post in bailout negotiations between Greece and international lenders. On Thursday she was charged by a prosecutor for breach of duty.