Bujumbura - Burundi's rival political factions met for crisis talks Wednesday mediated by Ugandan President Yoweri Museveni, a last-ditch effort following months of violence 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.
Previous United Nations-mediated efforts all collapsed, but Museveni arrived Tuesday for the latest bid to push stalled talks between Nkurunziza's ruling CNDD-FDD party and opposition groups.
"I urge the people of Burundi to forget their past sectarian political differences and build their country on unity," said Museveni, who was appointed mediator last week by the five-nation East African Community (EAC).
Warring political factions
Around a 100 people have been killed in more than two months of protests, with over 158 000 refugees fleeing to neighbouring countries, according to the UN.
Gunfire and grenade explosions were heard overnight on Tuesday in the capital, as has been common in recent weeks.
The veteran Ugandan leader, who first flew to Rwanda for meetings before entering Burundi escorted by Ugandan armoured vehicles on Tuesday, has said he is working to "establish a dialogue among warring political factions."
But with the presidential election now taking place on Tuesday, Museveni has been left with only a few days to succeed, and little sign the rivals will soften positions to find agreement.
'Beginning of something much worse'
Polls, originally due on Wednesday, were pushed back by six days amid intense international pressure.
But a group of 17 aid agencies and rights groups warned Wednesday that was "an insufficient gesture that ignores the risk that elections could spark major violence."
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Opposition groups say another term would violate a peace deal that paved the way to end a dozen years of civil war in 2006. There are fears the current crisis could plunge the impoverished, landlocked country back into civil war.
"Scores have already been killed, but this could be just the beginning of something much worse," said Ndung'u Wainaina, from the Kenya-based International Center for Policy and Conflict, a member of the coalition demanding further delays.
"In the current context of tensions and credible threats of further violence, holding elections next week could push Burundi into a much deeper crisis," Wainaina added.
Both sides have made clear that their positions will not change. Opposition groups said they would reject proposals for a government of national unity.
"A government of national unity cannot be based on legislative elections we have opposed," senior opposition leader Charles Nditije said.
"Whatever happens, we will continue our fight against the third term of Nkurunziza," opposition leader Leonce Ngendakumana told AFP.
Parliamentary polls, in which Nkurunziza's ruling CNDD-FDD scored a widely-expected landslide win, were held on May 29 but boycotted by the opposition and internationally condemned.
Troops clashed with suspected rebel fighters over the weekend in northern regions bordering Rwanda.
Burundian rebel general Leonard Ngendakumana - who took part in the failed coup in May to topple Nkurunziza - has confirmed that soldiers loyal to the coup plot were involved in the fighting.
Opposition and rights groups argue that weeks of protests and a violent crackdown by security forces mean free and fair elections are impossible.
Museveni, who has led Uganda since 1986 and is one of Africa's longest-serving rulers, is himself seeking re-election in polls next year.