An al-Jazeera television journalist and eight others have been remanded in custody in Spain ahead of a trial on charges of having links with al-Qaeda.
Alouni is said to have a heart condition that could worsen in jail
Tayseer Alouni, who holds dual Syrian and Spanish citizenship, was arrested on Thursday evening on his way home.
Prosecutors urged that he and the other eight remain in custody until their February trial for fear they may flee.
Lawyers for the nine criticised the order, saying they had abided by the conditions of bail set over a year ago.
The nine are among more than 35 people - including Osama Bin Laden - indicted on charges of belonging to or collaborating with al-Qaeda by Spanish judge Baltasar Garzon.
The Associated Press reports that 11 are already in jail, while 19 are still at large.
Mr Alouni - one of al-Jazeera's best known reporters - was charged last year with fundraising for al-Qaeda.
He is accused of using his reporting trips to Kabul in Afghanistan as a cover for his activities.
Mr Alouni was held overnight in police custody in his home city of Granada on Thursday before being transferred to the capital, Madrid, for Saturday's court appearance.
National Court Prosecutor Pedro Rubira argued for custody, as "the nearness of the trial increased the risk of flight from justice, especially given that the charges relate to a terrorist organisation that has the means to prevent its militants appearing before court and being tried".
Lawyers for the nine said they had no intention of trying to leave Spain, given that they had abided by their bail conditions and had lived and worked in the country for years.
"How am I going to run away?" Mr Alouni told the court, according to the leading daily El Pais. "If I flee, I risk my entire journalistic career."
Lawyers said Mr Alouni and another of the nine had health problems that could get worse in jail.