A judge sent two Moroccan brothers to jail Saturday on provisional charges of collaborating with a terrorist group in connection with the deadly Madrid train bombings (search) last year, but ordered their parents freed.

The family, detained Tuesday, was questioned overnight by a judge leading the probe into the March 11 bombings that killed 191 people and wounded more than 1,500, said an official at the National Court on condition of anonymity.

The brothers, Brahim and Mohamed Mousatten (search), are known to have had regular contacts with their maternal uncle Youssef Belhadj, 28, who authorities believe is an Al Qaeda figure mentioned in a video claiming responsibility for the attacks.

Belhadj was detained Tuesday in Belgium on an arrest warrant issued by Spain.

The court official said Belhadj visited Madrid a month before the attacks and stayed with his nephews. He left the Spanish capital hurriedly just before March 11.

The court official said a fugitive in the case, Mohamed Afalah (search), asked the two brothers how to reach Belhadj after seven suspects in the train bombing blew themselves up as police moved in to arrest them April 3 in Madrid.

Belhadj had close ties with the seven, the official said.

On Monday, judge Juan del Olmo is to question two other March 11 suspects arrested this week.

Rachid Mohamed Kaddur, a 35-year-old Spaniard, was arrested Thursday night in Melilla, one of two Spanish enclaves on the coast of Morocco. Rachid Bendouda was arrested Wednesday in the Madrid neighborhood of Lavapies. Both are believed to have met with key bombing suspect Abdennabi Kounjaa the day before the attacks.

Kounjaa was one of seven who committed suicide in Leganes.

Twenty-two suspects have been jailed over the March 11 attacks. More than 40 other people were also arrested and later freed, but are still considered suspects and remain under court supervision.