According to the prosecution, three stones were thrown from a petrol station at the convoy of about 50 vehicles as it drove through the northern town of Kayanza last Wednesday.
One stone hit a member of the presidential guard, another hit a windshield of one of the cars, and another did not hit anything.
Witnesses in Kayanza told AFP the convoy did not stop during the incident.
The Kayanza court on Sunday “sentenced three young people including a woman to 30 years in prison (each) for an attack and plot against the head of state,” a judicial source told AFP on condition of anonymity.
The information was confirmed to AFP by three witnesses present at the hearing.
The accused, two petrol pump attendants and a mechanic, were initially charged with “breach of public safety and not alerting the concerned services that the head of state was in danger.”
The prosecutor requested sentences of seven and a half years in prison, during Sunday’s hearing in which the accused appeared without legal assistance.
All three denied throwing the stones, or seeing who threw them.
However during her ruling, judge Marie-Goreth Ndayishimiye — not related to the president — announced the court had “decided to reclassify the charge as ‘an attack and plot against the head of state'”.
She then sentenced the three to 30 years in prison, without giving further explanation as to the change in the charge, said the judicial source.
The president’s spokesman Jean-Claude Karerwa Ndenzako did not respond to efforts to seek comment.
“This has confirmed that the Burundian government remains paranoid about such plots, and it is one of the first stains on the image of the new president and his slogan of fair justice,” an African diplomat said on condition of anonymity.
Ndayishimiye, a key member of the ruling party, was elected on May 20, and took office in June shortly after the shock death of his predecessor Pierre Nkurunziza.
The international community had hoped for a softening of the iron-fisted regime under a new president.
However Ndayishimiye has formed a government of hardliners, and has shown little sign of straying from the path of his predecessor.
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