By Njuwa Maina
BUJUMBURA (Reuters) - A senior Burundi army officer said on Wednesday he was dismissing Pierre Nkurunziza as president because his bid for a third term violated the constitution, and soldiers surrounded the state broadcaster building in the capital.
The presidential office quickly rubbished the declaration by Major General Godefroid Niyombare, who was fired by Nkurunziza as intelligence chief in February, as "a joke".
Niyombare made his declaration to reporters at a military barracks in the capital, while the president was out of the country at an African summit on the crisis.
Niyombare, also a former ambassador to Kenya, was surrounded by several other senior officers in the army and police, including a former defense minister.
"Regarding President Nkurunziza's arrogance and defiance of the international community which advised him to respect the constitution and Arusha peace agreement, the committee for the establishment of the national concord decide: President Nkurunziza is dismissed, his government is dismissed too," he said.
More than 20 people have been killed since street protests erupted in the impoverished central African state more than two weeks ago, according to an unofficial count by activists.
The demonstrators say Nkurunziza's bid for another five years in office violates a two-term limit in the constitution and the Arusha peace deal, which ended an ethnically fueled civil war in 2005 that killed 300,000 people.
Western donors, including the United States, have criticized Nkurunziza's decision to stand again.
East African leaders and a top official from continental heavyweight South Africa were meeting in Tanzania's commercial capital Dar es Salaam to discuss the crisis that has already spilled over into a region with a history of ethnic conflict.
More than 50,000 people have fled to neighboring states. The U.N. refugee agency UNHCR said the crisis was heading toward a "worst case scenario" that could see 300,000 people fleeing, some to other parts of Burundi and others abroad.
(Additional reporting by Goran Tomasevic in Bujumbura, Fumbuka Ng'wanakilala in Dar es Salaam and Tom Miles in Geneva; Writing by Edmund Blair; Editing by Andrew Heavens)