By Clement Manirabarusha and Edmund Blair
BUJUMBURA (Reuters) - Burundi's opposition has urged voters to follow their lead and boycott the presidential election scheduled for Tuesday, saying the vote will deepen political deadlock in a nation with a long history of political violence and ethnic strife.
President Pierre Nkurunziza's decision to seek a third-term in office has plunged the East African nation into its worst crisis since an ethnically charged civil war ended in 2005. Though street protests and a would-be coup were quelled, almost daily violence has left the country tense.
A grenade exploded in the centre of the capital but caused no casualties, deputy police spokesman Pierre Nkurikiye said. Grenade blasts marred a June parliamentary poll, which the opposition also boycotted.
Diplomats worry that the disorder may see Burundi slide back into civil war, a frightening prospect for a Great Lakes region still scarred by the 1994 Rwandan genocide in which about 800,000 Tutsis and moderate Hutus were killed.
Nkurunziza's government has pledged to push ahead with Tuesday's election, ignoring calls from the African Union (AU), United States and other Western powers for the vote to be delayed due to growing insecurity.
Officials have promised a free and fair election.
Charles Nditije, leader of the Uprona party, which is part of the opposition Amizero Y'abarundi coalition, called on foreign governments not to recognise a vote in which Nkurunziza will stand unopposed after the opposition withdrew from the race.
"I am urging Burundi citizens not to go to polls this July 21 which are not democratic," he told Reuters by telephone in the capital Bujumbura.
The electoral commission has said opposition candidates names are already on the ballot paper and any votes cast for them will be counted. The commission also counted votes for the opposition in the parliamentary poll. Nkurunziza's party won.
An AU official on Monday confirmed the regional body would not be sending election monitors to Burundi because "the conditions are not conducive for credible, transparent, free and fair elections".
Jacob Enoh Eben, spokesman for African Union Commission Chairperson Nkosazana Dlamini-Zuma, said that if the vote went ahead the AU would meet to discuss the way forward.
Opposition parties say Nkurunziza's re-election bid is unconstitutional and are boycotting the election race. The president cites a court ruling declaring he can run for five more years in office.
Months of talks between the two sides have yielded almost no results, and the latest negotiations broke down on Sunday when the government mediator did not show up for discussions.
Government spokesman Philippe Nzobonariba said the vote, which was delayed from June 26, would not be put back again and he urged Burundians to go to the polls "en masse to express their legitimate will".