By William Maclean KINSHASA, April 30 (Reuters) - A U.N. Security Council mission opened closed-door talks with Congo's President Joseph Kabila on Tuesday to revive efforts to end Africa's biggest war after the main rebel group rejected a partial peace deal as a sham. The team of 15 diplomats from the world's top security body was led into talks with Kabila by delegation leader Jean-David Levitte, France's U.N. ambassador. Government officials told reporters Kabila would issue a comprehensive statement on the peace process after the talks with the U.N. team, which will also visit Angola, Burundi, Rwanda, Tanzania and Uganda....