MADRID - Spain's High Court released one of the 29 suspects charged in connection with the 2004 Madrid train bombings on Wednesday after authorities failed to apply for the power to hold him for longer.

Saed El Harrak was set free after completing the maximum two-year period for which suspects can be kept in prison without trial. Authorities can apply for the power to hold suspects for a further two years, something they failed to do.

El Harrak was arrested after telephone records showed he called several men implicated in the attacks that killed 191 people, days before the event.

His number was also found in the rubble of a flat where suspects blew themselves up as police closed in on them a month after the commuter train blasts. El Harrak later admitted he knew one of men who committed suicide in the flat explosion.

Judge Teresa Palacios, who took the decision to release him as investigating judge Juan del Olmo was ill, said El Harrak would have to register with police twice a day, hand in his passport and is banned from leaving the Madrid region.

Court sources said Spain's highest judicial body could launch disciplinary proceedings against Del Olmo and the public prosecutor to find out how responsible they were in failing to apply for powers to hold El Harrak for longer.

The Madrid bombings, the worst attacks by Muslim militants in the West since the September 11 hijackings in the United States, helped sweep Spain's Socialist party to power on a wave of voter anger at the ruling conservatives.