Six people, including one police officer, have been killed in gun battles in Burundi's capital as the nation awaits election results from Monday’s parliamentary poll.

The clashes in Bujumbura’s Cibitoke district on Wednesday took place after three grenades were thrown at a police patrol, injuring two officers, a police official said speaking on condition of anonymity.

"Two policemen were injured,” said Fabien, a resident of Mutakura district where weeks of street protests took place against Nkurunziza in May and early June.

Fabien said it appeared some civilians were also wounded when two grenades exploded but it was not clear how many.

Other media reports yesterday indicated that up to 20 people had died after an alleged police raid on civilian homes turned violent in parts of Bujumbura on the day President Pierre Nkurunziza led the country’s 53rd Independence Day celebrations.

Reports from Mutakura and Cibitoke indicated that officers had forced their way into the commune.

A source in Mutakura, a district known for having been the stage of some of the protests against the president’s contested third term bid, said "around 20 people” had been found dead, including civilians and officers, after police entered homes in an apparent raid, prompting many residents to flee.

Elsewhere in the capital, military parades were held to mark the country's independence day.

The violence in the capital is the latest in weeks of unrest that has seen Burundi locked in its worst political crisis since its civil war ended a decade ago, with protests erupting in late April against President Pierre Nkurunziza’s bid to seek a third term in office.

Monday’s parliamentary elections were widely boycotted by the opposition and condemned internationally.Some voting stations were also attacked with grenades, according to the police.

The election commission claimed an "enormous” turnout in the local and general elections, despite many polling stations appearing quiet.

The US and other Western powers have criticised Monday’s poll, saying the conditions were not right to stage a fair election.

The electoral commission said it expected results from the poll to be announced yesterday or today.

Although the opposition boycotted the race, names of the parties were still on the ballot paper.

About 140,000 Burundians have fled across the country’s borders, including over 43,000 to Rwanda.