The Commando leader was found in Liverpool, where he had been hiding out since escaping custody in 1995.

Raúl Fuentes Villota, part of the 'Matalaz' Commando, was arrested in 1991 along with Juan María San Pedro Blanco and Germán Urizar de Paz for the attempted murder of a police officer in Barakaldo (Vizcaya) in the Basque Country.

They were taken into custody after firing shots at the police who tried to detain them.

Fuentes Villota was released on parole, along with five other members of the 'Matalaz' Commando, in 1995, since the case had not yet come to trial and he had been in custody for the maximum permitted period without a sentence.

Once released, he disappeared.

This week he was found in Liverpool, where he had been living since going on the run.

It is not known yet whether he will be extradited to Spain.

Fuentes Villota, 45, is the fifth ETA terrorist to have been arrested in the UK.

The most recent was Kemen Uranga Artola on August 8 in London, who is suspected of being behind the murder of magistrate José María Lidón in 2001 in Getxo (Bilbao) in the Basque Country.

On the day of Uranga's arrest, the then minister of the interior Jorge Fernández Díaz, telephoned his British counterpart Theresa May to thank UK authorities in their constant fight against the separatist terrorist organisation.

Photograph of Raúl Fuentes Villota supplied by Spain's ministry of the interior