An Egyptian who allegedly bragged that he masterminded the 2004 Madrid terror bombings that killed 191 people was acquitted of all charges along with six other lesser suspects Wednesday.

But the Spanish judge  found 21 people guilty in one of Europe's worst terrorist atrocities in recent years.

To the consternation of some survivors and relatives of the victims, one of the accused masterminds, Rabei Osman Sayed Ahmed, known as “Mohamed the Egyptian”, was acquitted along with six others. He is in prison in Milan, Italy, after being convicted of belonging to an international terrorist group. A representative from a victims’ association said he was unhappy that some of the accused were still walking free.

Three of the eight lead defendants — Emilio Trashorras, a Spaniard, and Jamal Zougam and Othman el-Gnaoui, both Moroccans — received sentences of nearly 40,000 years each. Under Spanish law, however, they can only serve a maximum of 40 years.

Rafa Zouhier was also found guilty of obtaining explosives and received a 10-year jail sentence. Fourteen others were found guilty of lesser charges such as belonging to a terrorist group. Judge Javier Gomez Bermudez spent more than an hour summing up the case before delivering verdicts on each of the accused. He also announced compensation for victims ranging from 30,000 euros to 1.5m euros.

Earlier, the defendants were driven to the court on the outskirts of Madrid under high security as helicopters buzzed overhead and scores of police officers stood guard.

The verdicts and sentences were the culmination of nearly five months of testimony by hundreds of witnesses, arguments by more than 40 attorneys, and sporadic hunger strikes by several of the 28 accused.

The defendants were variously accused of masterminding, carrying out or helping to prepare the attacks on four packed commuter trains heading into Madrid from working-class neighbourhoods during the morning rush hour of March 11 2004.

Prosecutors sought symbolic sentences of up to 38,976 years each for the eight lead defendants — 30 years for each of the people killed in the attacks, 18 years for each of the wounded, plus more time for other terrorism-related charges. Spain has no death penalty or life imprisonment.

Nine of the 28 defendants, including one woman, were Spaniards charged with supplying stolen dynamite used in the string of rapid-fire explosions.