MORE ON SPANISH PRISONS providing pool of recruits for radical Islam; today it's the New York Times:

Rather than scan all of society for recruits, Islamic militants in Spain have found that many of the most promising candidates have already been collected into one bountiful pool, law enforcement experts say.

It is the Spanish prison system, which has become increasingly populated with immigrants from North Africa, many possessing the characteristics that the recruiters are seeking, the law enforcement experts say. The prisoners are often Muslims, even if largely lapsed ones, and they are often bitter about their experiences in the West or their prison experiences.

The Spanish police announced Thursday that they had arrested 13 people they suspected of belonging to a terrorist cell made up almost entirely of North African immigrants recruited in a Spanish prison.

The group, which included 18 others arrested two weeks ago, began as a collection of unacquainted men jailed for minor criminal offenses like weapons possession, document fraud or robbery, the police said.

But their time in prison transformed them into the Martyrs for Morocco, a terrorist group planning to blow up the national court in Madrid, investigators said.

"It has confirmed that the nucleus for recruitment is centered on people convicted of common crimes," Baltasar Garzón, the judge investigating the case, said in a report released this week. He urged the government to tighten controls on the prison population here.

Previous posts on this issue: one, two, three and four.