The trial of 29 suspects in the 2004 Madrid terrorist attacks began Thursday under tight security, with survivors and mourners getting their first close-up look at the defendants accused of a massacre that killed 191 people and wounded more than 1,800.

An Egyptian accused of being one of the masterminds was among those who took the stand. He told the court he had no involvement in the bombings, despite intercepted conversations in which he allegedly bragged that he was the brains behind them.

"Your honor, I never had any relation to the events which occurred in Madrid," Rabei Osman said under questioning from his defense attorney.

He later condemned the attack, which killed 191 people and wounded more than 1,800 in March 2004. "Obviously I condemn these attacks unconditionally and completely. This is a conviction I have very clearly and absolutely," Osman said. He spoke in Arabic and his words were translated into Spanish.

Osman was arrested in Milan, Italy, in June 2004 on a warrant from Spanish authorities. Of 29 people who went on trial here Thursday, he is one of three accused of masterminding the attacks.

Italian prosecutors have said they tapped phone conservations in which Osman told an associate in Italy "I'm the thread to Madrid, it's my work."

The bombings were the worst-ever attack linked to Islamic militants in Europe, and the trial has dredged up painful memories of what Spaniards call the nation's most traumatic event since the 1930s civil war. Images of body bags and twisted train cars were played and replayed on Spanish television on Thursday, a grim reminder of the devastation left by 10 backpack bombs that exploded on four commuter trains during morning rush hour.

The first defendant to take the stand, Egyptian Rabei Osman, refused to answer any questions — even from his own lawyer — and said he did not recognize the charges against him.

"Your honor, with all due respect, I do not acknowledge any accusations or charges," Osman said calmly. "I am not going to answer any questions, including from my defense attorney."

When Osman tried to explain his reasons, a judge cut him off and ordered the prosecutor to pose the questions she had planned. Osman, who was arrested in Italy and later convicted of terrorism, allegedly bragged in intercepted phone calls that the Madrid train bombings were his idea, and is charged as an alleged ringleader.

Eighteen of the suspects watched the proceedings from a bulletproof chamber, packed together on wooden benches, while the other 11, who are out on bail, sat in the main section of the courtroom.

Many of the suspects in the bulletproof chamber averted their glance from victims' relatives sitting in the small, heavily guarded courtroom, and some even turned their backs to them.

Conchi Decos, who lost her husband in the attacks and was inside the courtroom Thursday, said her heart dropped when the suspects filed in. "You want to insult them, to say what you think. But instead we just said it quietly to ourselves," she told The Associated Press during a break in the proceedings.

Pilar Manjon, president of an association of March 11 victims, who lost her 20-year-old son in the massacre, said she stood up to get a better view when the defendants came in. "They lowered their heads," she said.

Seven lead defendants face possible prison terms of 30 years for each of the killings and 18 years apiece for 1,820 attempted murders. But under Spanish law, the maximum time anyone can serve for a terrorist conviction is 40 years.

Security was extremely tight for the trial, with police on horseback patrolling outside the court on the city outskirts, and bomb-sniffing dogs searching for explosives.

Testimony was expected to last more than five months, and a verdict was expected in late October.

The trial marks the culmination of a lengthy investigation, which concluded that the attack was carried out by a homegrown cell of Muslim extremists angry over the then-conservative Spanish government's support for the Iraq war and its troop presence in Afghanistan. The cell was inspired by Al Qaeda, but had no direct links to it, nor did it receive financing from Usama bin Laden's terrorist organization, Spanish investigators say.

That government initially blamed Basque separatists, and continued to do so even as evidence emerged of Islamic radical involvement. This led to charges of a cover up, and in elections three days after the attack Socialists were voted into power. They quickly brought Spain's troops home from Iraq.

The Madrid attacks were the deadliest in western Europe since the bombing of Pan Am Flight 103 over Lockerbie, Scotland, in 1988 that killed 270 people.

Of 12 suspected ringleaders, only three would be in court. Seven others blew themselves up to avoid arrest three weeks after the attack and the rest are fugitives.

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