Three Basque parties, including Herri Batasuna, now hold 41 of the assembly's 75 seats.

ECONOMIST: Spain and the Basques

Some, including Mr Ibarretxe, are still urging Herri Batasuna to condemn the violence and join mooted all-party talks.

ECONOMIST: Spain

Aznar blasted ETA's political arm, Herri Batasuna, calling them "accomplices" to the murder and asking Spaniards to isolate them.

CNN: Spanish king speaks out to condemn terrorism

He said Herri Batasuna would continue to work for peace and maintain its links with the main Basque nationalist parties.

BBC: ETA political wing calls for calm

Now he has called on his party to stop co-operating with Herri Batasuna in local councils, where the extremists have strongest roots.

ECONOMIST: Spain

Mr Ibarretxe put his Basque regional government together in the autumn of 1998 with support from Herri Batasuna and a smaller nationalist splinter.

ECONOMIST: Spain

Earlier a senior member of Herri Batasuna, Patxi Zabaleta, said there were no political reasons to justify ETA's decision which went against the will of the Basque people.

BBC: ETA political wing calls for calm

Meanwhile, since the Basque Nationalists are no longer co-operating with Herri Batasuna in the Basque parliament, they are now a minority government which could, at any time, fall to a vote of no confidence.

ECONOMIST: Spain