MADRID, Spain (CNN) -- Spain's interior minister said the suspects in a Barcelona terror plot were clearly ready to strike, but police have not yet found explosives "in sufficient quantity" to be used for the assault.
Spanish police move suspected terrorist detainees following last weekend's arrests in Barcelona.
"This cell was preparing to attack. It's clear they were going to try, whether last weekend or within 15 days," Interior Minister Alfredo Perez Rubalcaba said on Friday in an interview with Spanish radio network SER, which CNN monitored.
The 10 men, mainly Pakistanis, were arrested last weekend in Barcelona, and appeared on Wednesday before Judge Ismael Moreno, who ordered them to be held in prison.
In his rulings, Moreno wrote they were planning an attack between Jan. 18 and Jan. 20 against public transport in Barcelona, but police moved in first to make arrests.
An informant told authorities that the attack would be against Barcelona's metro system last weekend, Rubalcaba said in the radio interview. The informant, he added, also told authorities about potential links between the Barcelona group and suspected extremists in other countries, and that's under investigation.
But for now, Rubalcaba said, "there is only the testimony of an informant" regarding the imminent nature of the attacks.
"We have found a modest quantity of explosives," Rubalcaba said, adding that may have been used for training the suspects.
The judge in his rulings wrote that the group "had achieved human operational capacity and were very close to achieving full technical capacity with explosives, with the aim of using those explosives for a jihadi terrorist attack."
Rubalcaba said that for a suspected terrorist cell like this one, "the time from getting explosives to carrying out the attack can be very short."
The judge, in rulings viewed by CNN, wrote that police found nitrocellulose and mechanical and electrical elements that could be used to make one or more bombs.
The judge also cited the informant for providing information that three of the men were suspected suicide bombers who had come to Barcelona from Pakistan since last October, and a fourth man was a suspected explosives expert. The judge cited two other men as ideological leaders of the group.
But Spain's attorney general, Candido Conde-Pumpido, later said publicly that there could have been six suicide bombers, two explosives experts and two ideologues.
Spain's largest circulation newspaper reported on Friday the informant worked for French intelligence, which could not immediately be independently confirmed.
A total of 14 men were arrested last weekend in Barcelona, but Civil Guard investigators released two before the arraignments began and the judge released two more after the arraignments, for lack of evidence, holding just 10 in prison.
More than 300 suspected Islamic extremists have been arrested in Spain since the Madrid train bombings killed 191 people and wounded more than 1,800 on March 11, 2004, Rubalcaba said in the radio interview.
Last October, more than a dozen Islamic extremists were convicted in Madrid for their roles in the train bombings.
Spain remains on "permanent alert" against Islamic terrorism. Al Qaeda communiques regularly make specific references to Spain.
"Contrary to the Madrid bombings and other plots in Spain over the past years, this plot involved not only individuals who were legal residents in the country but also individuals who apparently came to Spain explicitly for the purpose of carrying out a terrorist attack," said Fernando Reinares, an expert on international terrorism at the Royal Elcano Institute in Madrid, in an interview with CNN. E-mail to a friend