Last-ditch talks between Burundi's government and opposition aimed at resolving a major political crisis over President Pierre Nkurunziza's controversial re-election bid appear to be headed for failure, sources close to the negotiations said.

The closed-door talks, mediated by regional power Uganda, began earlier in the day but quickly descended into an acrimonious exchange with no sign of any consensus on how to end months of turmoil in the central African nation.

Burundian President Pierre Nkurunziza on Friday promised to deliver "five more years of peace" if he is re-elected next week, in the climax of a campaign marked by deadly street protests and an attempted coup.

Addressing hundreds of supporters in northern Cibitoke province and protected by large numbers of police and troops, the president said only his ruling party delivers stability and promised the region new roads, a hospital, electricity and schools.

Ugandan President Yoweri Museveni left crisis talks between Burundi’s rival political factions Wednesday without a deal, but last-ditch efforts following months of violence continued ahead of polls next week.

Burundian President Pierre Nkurunziza's bid to stand for a third consecutive five-year term in an election next Tuesday, despite a constitutional two-term limit, has sparked months of turmoil and an attempted coup in mid-May.

Ugandan President Yoweri Museveni flew to Burundi Tuesday for crisis talks, as President Pierre Nkurunziza readied for a third term bid in polls next week following months of violence.

Museveni, appointed mediator last week by the five-nation East African Community (EAC), is to push stalled talks between Nkurunziza's ruling CNDD-FDD party and opposition groups.

Security forces in Burundi said Monday they had arrested around 170 suspected rebels and seized a number of weapons in a crackdown ahead of next week's presidential elections.

The Burundian army spokesman, Colonel Gaspard Baratuza, said the rebels were detained after clashes in the northern provinces of Kayanza and Cibitoke.

Burundian soldiers clashed with gunmen Friday in a northern region near Rwanda, a local official and the military said, in the latest violence ahead of controversial elections due next week.

The crisis in Burundi revolves around President Pierre Nkurunziza's bid to stand for a third straight five-year term, which his opponents say is unconstitutional and violates a peace deal that ended a dozen years of civil war in 2006.

Burundi's government said Friday it backed regional calls to postpone controversial polls, but only by a few days, saying it had asked the election commission to implement the delay.

The crisis in the central African nation revolves around President Pierre Nkurunziza's third-term bid, which his opponents say is unconstitutional and violates a peace deal that brought an end to a dozen years of civil war in 2006.

Burundi's embattled president skipped key regional talks Monday to campaign for a controversial third term amid renewed rebel threats and international calls to delay the vote.

The crisis in the central African nation revolves around President Pierre Nkurunziza's third-term bid, which his opponents say is unconstitutional and violates a peace deal that brought an end to a dozen years of civil war in 2006.

Burundi's ruling party and its allies on Sunday told a United Nations mediator to step down, just two weeks after he was sent to help resolve the central African nation's political crisis.

Senegal's Abdoulaye Bathily was told to "resign from his post because he seriously lacked respect for the country's sovereignty," a spokesman for the ruling CNDD-FDD party, Gelase-Daniel Ndabirabe, told AFP.

U.N. observers have ruled that elections in Burundi that were wracked by violence and boycotted by the opposition were not free or credible, a U.N. spokesman said Thursday.

"The overall environment was not conducive for free, credible and inclusive elections," U.N. spokesman Farhan Haq said.