Four men have had their convictions for participating in the 2004 Madrid train bombings quashed by Spain's top appeals court — bringing to 11 the number of people acquitted in connection with one of Europe's worst terrorist massacres.

Three Arab men were cleared yesterday of belonging to the radical Islamist cell that carried out the March 11 bombings, killing 191 people and injuring 1,800. A Spanish man was also cleared of trafficking explosives.

In a further blow for the Spanish prosecutor, the court upheld the acquittal of a man known as “Mohammed the Egyptian” , one of the alleged masterminds of the atrocity.

Yesterday's ruling disappointed victims of the bombings, who had already been shocked by many of the sentences handed down in October 2007.

After a sprawling investigation and complex trial, the court found 21 people guilty of involvement in the attack. Three men — two Moroccans, and a Spaniard who provided the bombers with explosives — were given sentences that should keep them in prison for 40 years, the maximum allowed under Spanish law.

The court cleared three men of masterminding the attack and acquitted seven others. Many of the sentences that were handed down were far more lenient than the public prosecutor had sought.

Yesterday the court cleared Basel Ghalyoun and Mohamed Almallah Dabas, both sentenced earlier to 12 years for belonging to a terrorist group; Abdelilah El Fadual El Akil, sentenced to nine years for collaborating with a terrorist group, and Raúl González, who received five years for supplying explosives.

Police defended their investigation and the trial, which was beset by angry political arguments and a battery of conspiracy theories. “No terrorist attack of this magnitude has been investigated so well, with so many people investigated and accused in such a short space of time,” José Manuel Sánchez Fornet, the general secretary of the police union, said.

Pilar Manjón, who lost her son in the attacks and became one of the victims' most eloquent representatives, was disappointed in her efforts to get an accused ringleader behind bars. Jesús Ramírez, a survivor of the attacks, said that he accepted the judges' verdict even if he did not agree with it: “Even though we may oppose it in our hearts, they have more information and have weighed the evidence and made a decision.”

After several suspected ringleaders blew themselves up during a raid by Spanish commandos days after the bombings, “The Egyptian” was the most senior figure charged with involvement in the attack. Italian police said that the man - whose real name is Rabei Osman Sayed Ahmed - was recorded in his Milan flat taking credit for the bombings while he watched a video of the US hostage Nicholas Berg being beheaded in Iraq.

The court upheld the ruling that he could not be convicted of belonging to a terrorist group because he was already in jail in Italy on that charge.

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