Interior Minister Alfredo Perez Rubalcaba said police who staged raids on Saturday in Barcelona and made the arrests did not find enough explosives "to infer an attack was imminent." The raids were prompted only by a tip-off from a police informant, Rubalcaba said.
Judge Ismael Moreno of the National Court ordered the detainees - nine Pakistanis and an Indian - jailed on Wednesday night pending further investigation.
Moreno said the group had only a small amount of bomb-making material that was not enough for a major attack. But he said three members of the cell had planned suicide bombings against Barcelona's public transport network to take place on the weekend they were arrested.
Spanish Attorney General Candido Conde-Pumpido also has said attacks were imminent.
The interior minister said Friday that officials believe the police informant is credible but "there are doubts" about how close the cell was to acting.
Rubalcaba told Cadena Ser radio that the cell was probably using the explosives for training purposes but would have attacked soon.
"From the moment a cell like this decides to attack to when it actually does, not much time goes by," the minister said.
The minister said police were looking for explosives that the cell would have needed to attack.
A discrepancy has emerged over how many cell members allegedly planned to blow themselves up. The judge said three, but the attorney general said six.
Conde-Pumpido's office said Friday this was due to a difference in how the two men interpret evidence gathered by police investigators.
Europe's worst Islamic-linked terror attack took place in Madrid on March 11, 2004, when bombs went off in four trains, killing 191 people. Last year, 21 suspects were convicted of terrorism and other charges in the bombings.
