A man who claims to be the mastermind of the Madrid train bombings has been giving eavesdropping Italian investigators new insights into the murky world of terrorism.

Rabei Osman Ahmed (search), a 33-year-old man known as "Muhammad the Egyptian," was arrested June 7 on an international warrant issued by Spanish authorities. The Italians also detained a 21-year-old Palestinian, Yahia Payumi (search), as an alleged accomplice.

For weeks before Ahmed's arrest, and while in custody, Italian investigators monitored his conversations. He was picked up after wiretaps indicated he was planning another attack in an undisclosed location.

The day after his arrest, Italian Interior Minister Giuseppe Pisanu (search) said Osman Ahmed was "probably among the principal authors" of the Madrid bombings, and that he "was preparing other attacks."

Pisanu did not elaborate, and Italian authorities denied published reports that the Paris subway system was the probable target.

The March 11 bombs, planted on four commuter trains in Madrid, killed 190 people and injured more than 2,000.

"The Madrid attack is my project," the Egyptian told the Palestinian after his arrest, according to a transcript published last week in the Milan newspaper Corriere della Sera. "The project has cost me a lot of study — it took me 2½ years."

"Some have died like martyrs, eight others have been arrested. They are my best friends," according to the transcripts.

No terrorists are believed to have died in the attack, but seven suspects blew themselves up in an apartment near Madrid as police prepared to storm it in connection with the bombings.

Fifty-one people have been detained in Spain in connection with the attacks, including a new suspect arrested Monday near the Madrid suburb of Leganes — where the seven suspects killed themselves. Sixteen of those — mostly Moroccans — are in jail on provisional charges.

In the wiretaps, the Egyptian speaks of his efforts to recruit suicide bombers and the importance of martyrdom. But, after his arrest, he said he expected a sentence of "at least 30 years. I, too, am implicated."

Investigators also found that he had downloaded from the Internet pictures of suitcases full of explosives and of an explosives vest. He also had a video of the decapitation of Nicholas Berg (search), an American killed in Iraq in May, officials said.

An inspection of the computer found it linked to Islamic extremist sites, the authorities said.

Spain is seeking Osman Ahmed's extradition, but he is fighting it. In turning down a defense request for his release, the court said the wiretaps show he was a man of "extraordinary danger," Corriere della Sera said.

Spanish Interior Minister Jose Antonio Alonso denied there was any disagreement with Italy over the affair.

"We fulfilled our part in the affair, which was asking for the extradition, and we hope the Italian authorities make their decision taking this into account," he said.