U.N.concerned by Machar delay in return to South Sudan capital

By Michelle Nichols UNITED NATIONS (Reuters) - The United Nations Security Council expressed serious concern on Tuesday over the failure of South Sudanese rebel leader Riek Machar to return to Juba to take up his old post as deputy to President Salva Kiir as part of a peace deal. U.N. peacekeeping chief Herve Ladsous briefed the 15-member council on South Sudan at the request of the United States.