NAIROBI, Dec 30 - President Mwai Kibaki beat opposition rival Raila Odinga by a narrow margin to win re-election in Kenya’s closest ever vote, the head of the country’s electoral commission (ECK) said on Sunday.

Thousands of pro-opposition protesters immediately launched angry demonstrations, burning shacks in the capital’s Kibera slum. Odinga has accused the government of widespread rigging -- allegations that had already fuelled two days of ethnic riots.