Ten Burundian army and police officers have deserted the security forces since the beginning of this month, an army spokesman said Friday.
Security expert Gratien Rukindikiza put the number at 13 and said they feared repression for their ethnicity or for being perceived as opposition supporters.
The officers, who have reportedly gone into exile, include several senior ones. Their departure followed that of Colonel Adolphe Manirakiza, a former spokesman for the UN peacekeeping mission in the Central African Republic, in April.
In May, a court handed life sentences to 21 people, including senior military officers, who had been implicated in a failed coup attempt against President Pierre Nkurunziza in May 2015.
Dozens of soldiers have been arrested since on charges of supporting the armed opposition, Rukindikiza said.
Many of the detainees belong to the minority Tutsi ethnic group.
But army spokesman Gaspard Baratuza denied that the deserters acted out of ethnic or security motives and said they were being manipulated by the opposition.
Burundi has been in turmoil since Nkurunziza announced last year that he would seek a third term in office despite a constitutional two-term limit.
His election victory in July 2015 unleashed a wave of political violence in which hundreds have been killed.
Human rights activists say the Hutu-dominated government is increasingly targeting Tutsis in an attempt to foment ethnic hatred and to deviate attention from the political conflict.