The army said the arrests were made in a rebel stronghold
Burundi's army says it has arrested more than 100 young people who were being recruited to join the country's last active rebel group.
The recruitment by the National Liberation Forces (FNL) violated a recent ceasefire that the group signed with the government, the army said.
But the FNL said those arrested were fighters on their way to assembly areas where they would be disarmed.
Burundi is emerging from more than 14 years of civil war.
The ceasefire, which was announced in May, was seen as the first step in implementing a 2006 peace agreement.
Army spokesman Adolphe Manirakiza said the FNL was trying to swell its ranks so it would get more posts in the Burundian army and government.
The army said the arrests had been made in a rebel stronghold 25 miles (40 km) south of the capital, Bujumbura.
But rebel spokesman Pasteur Habimana called for the immediate release of the detainees.
Some 300,000 people died in the war sparked in 1993 by the assassination of Burundi's first Hutu head of state and democratically elected president, Melchior Ndadaye.
Ex-rebel Pierre Nkurunziza was elected president in 2005 under a deal to end conflict between the Tutsi army and Hutu rebels.
This year, more than 100 people were killed and some 40,000 people displaced in renewed fighting that began in April.