Award-winning Mexican journalist Sanjuana Martinez has been released after being jailed for 24 hours by the judge handling her battle for custody of her children, the reporter's attorney said.

Martinez's husband, Spanish Judge Carlos Castresana, filed suit against Martinez to gain custody of their children, a case pending procedural issues and which could be moved to another court at the journalist's request.

"She's at home peacefully now with her kids," Martinez's attorney, Queeny Rose Osorio, told Efe.

The attorney said the journalist was arrested at around 2:00 p.m. Thursday and was let out of jail Friday at about 2:30 p.m.

The order for her release was handed down by a federal civil tribunal different from the court hearing the custody case, the attorney said.

Osorio indicated Thursday that Sanjuana Martinez's arrest might be linked to a report written by the journalist in 2008 about a raid on a shelter for women who had been victims of violence.

The raid was ordered by Judge Luz Maria Guerrero Delgado, the same jurist trying the case for custody of the journalist's children. The organization that owns the shelter reacted by suing the judge for abuse of power.

The investigative journalist's arrest was ordered due to her refusal to comply with Judge Guerrero's order to hand over her children, sources familiar with the case said.

Checking the facts with Judge Guerrero has proved impossible, since Efe's repeated phone calls to her since Thursday to ask about the state of the case and the situation of the journalist have gone unanswered.

Martinez had asked another court to take up the case. "The procedure is being looked into. Another kind of action will be taken," the journalist's attorney said, adding that the judge's actions entail some "pretty serious responsibilities."

Paris-based press freedom watchdog Reporters Without Borders, known by the French initials RSF, demanded Thursday the freeing of Sanjuana Martinez, who was arrested in the northern industrial city of Monterrey.

Martinez is a contributor to the daily La Jornada as well as to Proceso magazine, and is "noted for her campaigns on behalf of abused women and children," the RSF said.

"Does anyone seriously believe that three police officers were justified in marching Sanjuana Martinez off to jail like a common felon on the basis of civil proceedings that were in no way criminal in nature?" RSF asked rhetorically.

RSF also said that "the pretext is so implausible and misleading that it could be seen at best as personal revenge by the judge who ordered it, with whom the journalist is in serious dispute, or at worst as a desire to punish Sanjuana Martinez for her views and the stands she has taken."

Sanjuana Martinez, 49, was awarded Mexico's National Journalism Prize in 2006 and Spain's Ortega y Gasset Prize in 2008. EFE