A Spanish judge on Sunday started questioning 16 suspected Al Qaeda terrorists, who authorities say are possibly linked to the ricin poison case in Britain.

Police arrested them Friday at homes in Barcelona and other cities in northeast Spain and say they found explosives, chemicals, timers and other electronic equipment for making bombs, false passports and other documents.

They also said the 16 — 15 Algerians and a Moroccan — are linked to suspected terrorists arrested recently in Britain and France and were planning to attack unspecified targets.

Judge Guillermo Ruiz Polanco, who ordered the arrests on a petition from French judicial authorities, had wanted to start the questioning Saturday but put it off one day, national radio said. Police told him they needed more time to analyze the confiscated material and identify the suspects.

It was not known how long the questioning at the National Audience would take. It began around midday.

The French authorities who requested the arrests are investigating a foiled plot to attack targets in the French city of Strasbourg in 2001, the Spanish newspaper La Vanguardia said.

The suspects were brought to the court Sunday in white vans, accompanied by other vans with armed police.

After the questioning, the judge can either release them without charges or on bail, or jail them while he continues his probe.

U.S. officials have said the men may have links to the ricin poison case that emerged this month in Britain when that easy-to-make biological weapon was found in an apartment in London.

British authorities believe some of the suspects arrested in Spain had recently visited London, according to the Times newspaper in London.