Along with the EU and UN, African countries have urged Burundian factions to keep up dialogue. Opposition groups have vowed to boycott talks with the government after a dissident leader was shot dead on Saturday.
Burundi's opposition has suspended talks with President Pierre Nkurunziza's government after the murder of one of their leaders. Many anti-government leaders and activists have gone into hiding after Zedi Feruzi's death.
The UN refugee agency UNHCR says an outbreak of cholera has infected 3,000 people in a Tanzanian border region, where the population has increased dramatically due to an influx of refugees from Burundi.