Two of Burundi's vice presidents of the election commission have resigned and fled the country.

The vice president of Burundi's election commission has fled the country ahead of the poll, sources said on Saturday, amid a political crisis triggered by President Pierre Nkurunziza's decision to run for a third term.

Spes-Caritas Ndironkeye joins a senior judge and a host of dissidents who have fled the country following a failed coup attempt against Nkurunziza and as sometimes deadly protests against his decision to stand continue.

The political crisis is the biggest in the east African nation since its ethnically charged civil war ended in 2005.

"She fled the country with her daughter," said a relative of Ndironkeye who did not wish to be identified.

A spokesman for the electoral commission, known as CENI, Prosper Ntahorwamiye, said it had received similar information but had no evidence that Ndironkeye had fled the country.

It was not immediately clear if Ndironkeye's absence, if confirmed, would have any impact on parliamentary and local authority elections next week or the June 26 presidential vote.

On Thursday, the European Union and Burundi's influential Roman Catholic Church pulled out from observing the elections, saying next month's vote could not be fair because of daily unrest and a crackdown on media.

There were no protests in Bujumbura early on Saturday, with police manning several checkpoints on the roads.

Regional leaders from the East African Community common market will hold a summit in the Tanzanian capital on Sunday to discuss the crisis in Burundi.