BUJUMBURA - President Pierre Nkurunziza has pardoned "several thousand" prisoners in order to address prison overcrowding and celebrate Burundi's 50th anniversary of independence, his spokesman said.

"The President signed a decree pardoning prisoners in order to make space in the jails and to allow detainees to celebrate the 50th anniversary of independence along with us," Willy Nyamitwe, one of Nkurunziza's spokesmen said.

The decree states that those serving a term of five years or less are set free, along with women who are pregnant or breastfeeding, prisoners who are over 60 or under 18 and those suffering from terminal illness.

Those who were condemned to death before the abolition of the death penalty in April 2009 get their sentences commuted to life in prison; those sentenced to life get their term reduced to 20 years and prisoners serving terms shorter than life get their sentences reduced by half, Nyamitwe said.

The pardon does not however apply to prisoners serving time for armed robbery, illegal possession of firearms, threatening state security, war crimes, crimes against humanity or rape.

Nyamitwe said the pardon would take effect immediately and it would result in "several thousand" prisoners being freed.

At the end of May Burundi's prison population stood at 10,389, around half of whom had already been sentenced. They were crammed into 11 jails whose maximum total capacity was 3,500, according Aprodeh, a prisoners' rights group.

A former Belgian colony, Burundi will celebrate 50 years of independence at the beginning of July.