Security services detained Nourredine Boudiafi, head of the Armed Islamic Group (GIA), in the eastern Algiers suburb of Bab Ezzouar in November.

His deputy, Chaabane Younes, was killed in Chlef, 210km (160 miles) west of Algiers, the ministry added.

The GIA has already been weakened by internal rivalries, the statement said.

The ministry statement did not give precise details of Mr Boudiafi's arrest or of the killing of Mr Younes.

But it said his arrest followed the killing of Mr Boudiafi's predecessor, Rachid Ouakali, alias Abu Tourab, in July by his own men so that Mr Boudiafi could take over.

Waning power

The GIA was the most radical of Algeria's armed Islamic movements, says the BBC's Mohamed Arezki Himeur in Algiers.

It has been behind the majority of attacks and assassinations targeting intellectuals, journalists and foreigners.

The group was also responsible for the bloody hijacking of an Air France airbus in December 1994 at Algiers airport, and a series of civilian massacres in several parts of the country during the 1990s.

But its power started to wane at the end of the 1990s following the death of leader Djamel Zitouni by Islamic rivals in an ambush, says our correspondent.

The battle for the leadership led to internal divisions and rivalries that sparked the establishment of other armed groups.