Bujumbura: Burundi's authorities have arrested three generals for their role in an attempted coup but the leader of the bid to overthrow President Pierre Nkurunziza was ‘still on the run’, a presidential spokesman said on Friday.

After Thursday's heavy fighting for control of the state radio headquarters and frequent gunfire in the capital, the streets of Bujumbura were quiet on Friday morning.

Nkurunziza, who had been in Tanzania when Major General Godefroid Niyombare said on Wednesday he was leading a bid to overthrow him, came back to Burundi on Thursday, another signal that his government had regained control of the capital.

But the president has returned to face alarming splits in the military and a nation where thousands of protesters in Bujumbura capital had rallied against Nkurunziza's bid for a third term in office and cheered when the coup was declared.

The unrest has plunged Burundi into its deepest crisis since an ethnically fueled civil war ended in 2005.

Presidential spokesman Gervais Abayeho told Reuters one police general and two army generals had been arrested ‘for involvement in the aborted coup.’ Among them was former Defence Minister Cyrille Ndayirukiye, he said.

But coup leader Niyombare, who was fired from a briefly held post of intelligence chief by Nkurunziza in February, was not one of those held, he said. ‘His is still on the run. His whereabouts are not known to us,’ Abayeho added.

The coup followed more than two weeks of protests in Bujumbura, in which demonstrators often clashed with police, who were often seen firing live rounds at protesters.

More than 20 people were killed, according to an unofficial tally by activists.

The heavy-handed response of the police drew stern rebukes from Western donors, who have urged the president not to run again. The United States, which provides training and equipment to the army, demanded a halt to ‘violent force’ used by police.

The constitution and the Arusha peace deal that ended the civil war both set a two-term presidential limit.

The documents also outlined power sharing arrangements to end a conflict that had pitted rebel groups of the majority Hutus, including one led by Nkurunziza, against the then Tutsi-led army. The military is now mixed and absorbed rebel factions.

Nkurunziza justifies his bid for another five years in office by pointing to a constitutional court ruling which said the president could run because his first term, when he was picked by parliament rather than by popular vote, did not count.

Critics say the court is biased and donors have questioned the court's neutrality.