DAKAR (Reuters) - Suspected Christian militias killed an Egyptian U.N. peacekeeper and wounded three others in an attack in southern Central African Republic on Sunday, the United Nations said in a statement.  The attack, which the United Nations said was carried out by anti-balaka militants, occurred in Gambo, about 100 km (60 miles) from the town of Bangassou where more than 100 civilians and three Moroccan peacekeepers were killed in separate incidents in May and July.  Conflict has killed thousands in Central African Republic since Muslim Seleka rebels ousted President Francois Bozize in 2013, provoking a backlash from the Christian anti-balaka militia.  Violence spiked when former colonial power France ended its peacekeeping mission last year.  Since then, the United Nations  13,000-strong Central African Republic mission, known as MINUSCA, has struggled to restore order to a country where government control barely extends beyond the capital Bangui.  In total, 13 MINUSCA peacekeepers have been killed in the country this year alone.  Five militants were also killed during Sunday s clash, the United Nations said.  