Burundi's anti-corruption court has sentenced an anti-graft activist to five years in jail for "false declarations", a spokesman for the court said Tuesday.

Faustin Ndikumana and his organisation Parcem "were both found guilty of false declarations" under the anti-corruption law, spokesman Leandre Brampahije told AFP.

He said Ndikumana had been handed five years in jail and a fine equivalent to $350 (289 euros), while the organisation Parcem was given a fine of $3,500.

In addition, the pair were jointly ordered to pay $7,000 damages to Justice Minister Pascal Barandagiye, he said.

Ndikumana's defence lawyer Lambert Nsabimana told AFP his client would appeal the ruling. He had been out on bail, and was understood still not to be in custody.

Ndikumana was arrested February 7 after writing a letter in which he said candidates for the post of judge in Burundi had to pay a bribe, and that the justice minister was in part responsible for this state of affairs.

"This sentence is a disgrace. Burundi is an upside-down world where whistleblowers are sentenced to jail rather than the corrupt officials they expose," said Gabriel Rufyiri a prominent activist who heads another anti-graft organisation.

He added that since 2006 Burundi has dropped from 32nd place to 10th place in a ranking of the world's most corrupt countries.