Burundian President Pierre Nkurunziza warned rebels Thursday that they would be crushed by God after being sworn in for a controversial third term following weeks of protests and a failed coup against him.

Nkurunziza thanked God for his win in elections last month -- polls the United Nations say were not free or fair -- after taking the oath of office in a surprise ceremony in the capital Bujumbura announced only hours before.

Top envoys warned Wednesday that Burundi's government showed a "disturbing intent" on scrapping ethnic quotas in positions of power, a key pillar of a peace deal that ended a 13-year war.

The diplomats, from the United Nations, African Union, European Union, Belgium and United States, called on all sides to "recommit to a transparent, inclusive, and comprehensive political dialogue".

The U.N. Security Council on Monday demanded that Burundi's government immediately reopen talks with the opposition to put a halt to a spiral of violence that is pushing the country to the brink.

The 15-member council backed plans by Secretary-General Ban Ki-moon to send a high-level U.N. official on an urgent mission to ease the Burundi crisis.

Burundi's main opposition leader Agathon Rwasa was Thursday elected as deputy head of the national parliament, despite having condemned recent elections and supported months of civil unrest.

Rwasa, who has denounced the third consecutive term win by President Pierre Nkurunziza, had said earlier this week that he intended to "play the game" in order to try and help find a solution to the country's political crisis -- but has already been branded a "traitor" by other opposition figures.

Burundian President Pierre Nkurunziza was Friday declared the outright winner of controversial elections, handing him a third consecutive term at the helm of the central African nation despite opposition protests and international condemnation.

Nkurunziza won 69.41 percent of the vote in Tuesday's polls, handing him an immediate first-round victory, the election commission said. 

U.N. chief Ban Ki-moon on Wednesday urged calm and a political dialogue in Burundi after controversial presidential elections held against a backdrop of violence and international condemnation.

Protests against President Pierre Nkurunziza and his bid for a third-term have been violently repressed, leaving at least 100 people dead since late April.

Burundi counted votes Wednesday a day after a presidential election marred by violence and international condemnation that is expected to see incumbent Pierre Nkurunziza win a controversial third term.

Results from the polls, which were condemned as illegitimate by the international community after sparking months of deadly violence that forced tens of thousands to flee the country, are expected on Friday.

The United States said Burundi's elections Tuesday lacked credibility and by pressing ahead, the government "risks its legitimacy."

The voting "will further discredit the government," State Department spokesman John Kirby said, after polling went ahead despite opposition protests that President Pierre Nkurunziza's candidacy was unconstitutional.

Burundians voted Tuesday amid gunfire and grenade blasts, with President Pierre Nkurunziza widely expected to win a third consecutive term despite international condemnation and thousands of people fleeing feared violence.

At least two people -- a policeman and a civilian -- were killed in a string of explosions and gunfire overnight Monday, with blasts and shootings heard as polls opened shortly after dawn in the capital Bujumbura, the epicentre of three months of anti-government protests.

Talks between Burundi's government and opposition aimed at resolving a major crisis over President Pierre Nkurunziza's controversial re-election bid were suspended on Sunday less than 48 hours before the central African nation goes to the polls.

The breakdown in the negotiations came after Burundi's government failed to turn up, said Ugandan defense minister and mediator Crispus Kiyonga. Earlier, the government said it wanted a pause and signaled it could abandon the process altogether.