More than 150 officers raided homes in the Basque provinces of Guipuzcoa and Navarra and the city of Seville after an order from judge Baltasar Garzon.

An interior ministry spokesman told Reuters news agency the arrests brought the number of suspected ETA members detained this year to 167.

ETA has killed hundreds during its 35-year campaign for a separate state.

'Weaker than ever'

Spanish Interior Minister Angel Acebes said the arrests dealt a significant blow to the organisation's infrastructure.

"International legal co-operation is suffocating ETA and the terrorists," he was quoted by Reuters as saying.

"Today ETA is weaker than ever, but unfortunately ETA still exists."

Last month police in Spain and France arrested 34 people suspected of links to the group.

Bloody campaign

Tuesday's raids were the results of information obtained from documents seized following the capture of alleged senior ETA member Ibon Fernandez de Iradi.

He was arrested in south-west France in December 2002, but escaped from a police station in Bayonne two days later and remains on the run.

He is believed to be a logistics chief, responsible for organising back-up for teams who carry out attacks across the Spanish-French border.