A senior US diplomat warned that if Burundi's president insists on staying for a third term in office, the country will become "difficult if not impossible" to govern.

US Assistant Secretary of State for Democracy, Human Rights and Labor, Tom Malinowski, told a news conference in Kinshasa, Democratic Republic of Congo:

"The resistance that [President Pierre Nkurunziza's] steps have generated among the population virtually guarantee that the country will be difficult, if not impossible to govern so long as he insists on maintaining his position."

Burundi's electoral body has delayed planned local and parliamentary elections in response to an appeal from African leaders, the head of the election body said on Wednesday (June 3), after more than a month of protests against the president's bid for a third term.

President Pierre Nkurunziza's decision to seek a third mandate has plunged the nation into its worst crisis since an ethnically charged civil war ended in 2005. The protesters say his move violates the constitution, which sets a two-term limit.

The almost daily protests erupted on April 26 and activists say more than 30 people have been killed so far, making the timetable that envisages a parliamentary vote on Friday (5 June) and a 26 June presidential poll appear increasingly untenable.

"I believe that there is still room for dialogue, particularly on the question of restraining security forces who have targeted civilians, on the question of restoring freedom of assembly, and the media outlets that have been closed down," said Malinowski.

"But on the question of the third term, it is hard to see a solution to the crisis in which power remains concentrated in one person forever in Burundi. The Arusha Accords need to be respected as part of any solution to this crisis," he continued to say.

With no sign of an end to the unrest, African leaders meeting at a summit in Tanzania called for a delay in the election timetable of at least a month and a half. Western donors and opposition parties have also urged a postponement.

Nkurunziza has previously defended his decision to run again by citing a constitutional court ruling saying he can do so, but the government has also said it is open to the idea of postponing the poll schedule.

However Malinowski said "the era of presidents for life in Africa and beyond Africa should be over", adding that the US will be "consistent in making this point whether the issue arises here or in other countries in the region or outside of Africa."

The violence in Burundi has unnerved a region with a history of ethnic conflict. Burundi has the same ethnic mix of majority Hutus and a Tutsi minority as Rwanda, where a 1994 genocide killed 800,000 people.