Bujumbura - Burundi's government on Sunday halted last-ditch negotiations with opposition parties aimed at resolving a major political crisis over President Pierre Nkurunziza's controversial re-election bid.Burundi's Interior Minister Edouard Nduwimana said regional power Uganda, which is trying to mediate the talks, had been asked to allow an "interruption" of the dialogue, and signalled that the government could abandon the negotiations altogether.The move comes two days before the central African nation is scheduled to vote in a presidential election that the opposition has vowed to boycott."We will use this interruption to determine if we will continue this dialogue, because we have seen that while we were in the process of talking, the others were preparing something else," the minister said.A source from the five-nation East African Community (EAC), which designated Uganda as the main mediator in the crisis, said the process now appeared to be "dead" - as Ugandan Defence Minister Crispus Kiyonga resumed talks with the opposition but without the government."The security situation could degenerate at any moment," the source warned.The crisis began in April when Nkurunziza announced his intention to stand for a third consecutive five-year term, despite a constitutional two-term limit, sparking months of street protests and a failed coup in mid-May.Opposition groups say another term would also violate a peace deal that paved the way to end a dozen years of civil war in 2006.During Saturday's talks, sources said the government side accused the opposition of siding with generals who led a failed coup in mid-May and who in recent weeks have revived their attempt to overthrow the president by launching armed rebel operations in the north.Mask now offThey cited an opposition statement calling for the creation of a common anti-Nkurunziza front that would also include Burundian exiles. The opposition has in turn accused the government of being unwilling to negotiate."Since the beginning they have been looking to stitch up the elections while at the same time give the appearance of negotiating. But the mask is now off," said Innocent Muhozi, a leading civil society campaigner.Three out of the eight presidential candidates have already pulled out of the race, leaving Nkurunziza on track for a near-certain victory but the country is deeply divided.There are fears the current crisis could plunge Burundi, which has a history of ethnic and political violence, back into war - adding another major crisis to the already unstable Great Lakes region.More than 150 000 people have fled the country because of the unrest, which has included a fierce government crackdown on demonstrations that left at least 100 dead.