The army has failed to end the more than 20-year-old war

Father Augustine Diamacoune Senghor was replaced by its secretary-general, Jean-Marie Francois Biagui.

A BBC correspondent says in recent years the group, which wants secession for Casamance, has become divided.

Peace deals signed in 2001 by Father Diamacoune with the government have further split the movement.

Unanimous decision

The new leader Mr Biagui favours holding further talks with the government on greater autonomy for Casamance.

But more radical splinter groups of the Movement for the Democratic Forces of the Casamance (MFDC) oppose negotiations.

The unanimous decision to retire Father Diamacoune was made at large meeting on Saturday in the regional capital, Ziguinchor.

Despite his failing health, the founding leader was made honorary MFDC president.

According to the BBC's Alpha Jallow in Ziguinchor, some MFDC members are not entirely happy with the move and fear it is an attempt by hardliners to prolong the Casamance crisis.

But in a statement Mr Biagui, said the MFDC now needs a new generation of leaders to amicably resolve the two-decade-old crisis.