Burundi's ruling party says all citizens of its former colonial power, Belgium, should leave the country.
Belgium last week said those "whose presence is not essential" should leave because of increasing levels of violence.
Burundi has accused Belgium of links to opposition groups it blames for a spate of killings.
The unrest began in April when President Pierre Nkurunziza announced he would seek a third term.
Belgium said it had about 500 citizens in Burundi but Robert Misigaro, from the BBC's Great Lakes Service, says there have been no signs of mass evacuations at the airport.