Slaves come from the poor communities in the north

The ceremony in Tahoua in central Niger was disrupted by police, who seized equipment from journalists.

In May this year, acting under pressure Niger's parliament banned the keeping or trading in slaves but the law has not been fully implemented.

Local human rights group say there are still some 20,000 slaves in Niger.

Tears of joy

The BBC's Idy Baraou says Governor Ziti Maiga sought to prevent journalists reporting on the ceremony, because he, along with many others in authority, does not accept that slavery still exists in Niger.

However, our reporters says the former slaves shed tears of joy as they were given certificates showing they were now free.

They were also given money to return to their homes.

According to a local anti-slavery organisation, Timidria, the victims are usually aged between 14 and 25.

Males slaves are forced to work in farms and tender cattle, while women are confined to domestic duties.

Castrated

The organisation says many female slaves are raped and subjected to other forms of sexual abuse by their masters.

Men who disobey orders are flogged or in serious instances castrated.

The slave drivers mainly target the less educated and poor members of the northern based tribes.

Freed slaves will now be able to move freely and will be allowed to own property in Niger.