Communications Minister Chyakh Ould Ely accused the party of being racist and violent.

In 1989, hundreds were killed and thousands deported to neighbouring Senegal after race riots in both countries followed a border conflict.

AC is the third party to be banned in recent years but Mr Ely said it would retain its four parliamentary seats.

'Dictatorial regime'

Mr Ely accused AC of trying to undermine national unity and threatening good relations with Senegal.

But, speaking in a BBC interview, the leader of Action for Change, Messaoud Ould Belkheir, denied this, and strongly criticised the government decree.

Belkheir says the ban is 'unjustified'

He called it "a typical example of the absence of democracy under a dictatorial regime that does not tolerate opinions opposed to its own."

He also said it was a response to gains by his party in both legislative and municipal elections held last October.

Mr Belkheir is himself a "Harratin" or descendant of slaves.

According to some estimates, black-skinned Harratin account for around a third of Mauritania's population.

Slavery has been outlawed three times but human rights groups say the practice still continues.

Lost land

Twelve years after the conflict with Senegal, thousands of black Mauritanian refugees still live in camps along the border, such as at Dagana.

The authorities say they are free to go back - if they can prove their citizenship.

The refugee children know only of life in camps

But they say their identity papers were confiscated when they were deported and their land has since been given to Arabs and Berbers.

In October 2000, another opposition party, the Union of Democratic Forces, was banned.

The pro-Iraqi Attalia party was outlawed in 1999 after protesting against the restoration of diplomatic ties with Israel by this Islamic state.