Latest: Judge orders two Barcelona terror suspects to be held without bail

Mr Andreu said there was enough evidence to hold 21-year-old Mohamed Houli Chemlal and 28-year-old Driss Oukabir on preliminary charges of causing homicides and injuries of a terrorist nature and of belonging to a terror organisation.

The judge said Houli Chemlal was also held for dealing with explosives.

Sahl El Karib, the owner of a cybercafe in Ripoll, the Pyrenees hometown to most of the members of the cell, will remain in custody under arrest for at least 72 more hours while police inquiries continue.

The judged ruled the evidence to keep holding suspect Mohamed Aalla was "not solid enough".

An extremist cell was preparing bombs for an imam who planned to blow himself up at a Barcelona monument, a key suspect in the attacks that killed 15 people in north-eastern Spain told a judge, according to a judicial official.

The suspect, Mohamed Houli Chemlal, 21, was one of four men brought before Spain's National Court in Madrid on Tuesday to testify about the Islamic extremist cell that attacked pedestrians in Barcelona and the nearby seaside town of Cambrils last week.

National Court Judge Fernando Andreu is scheduled to rule later on the prosecutor's request to send the four to jail without bail for preliminary accusations of being part of a terrorist organisation, homicide, causing havoc and dealing with explosives.

A Spanish judicial official said Houli Chemlal and suspect Driss Oukabir, 28, identified the imam, Abdelbaki Es Satty, as the ideologist of the cell.

Oukabir and the other two surviving suspects who testified on Tuesday, Mohamed Aalla and Sahal El Karib, denied being part of the cell, said the court official.

Eight members of the cell have either been killed by police - five were shot dead on Friday and one on Monday after a manhunt - or accidently blew themselves up, like Es Satty and another man, while preparing explosives in a house in the coastal town of Alcanar, south of Barcelona.

Es Satty preached in a mosque in the north-eastern town of Ripoll, home to most of the 12 pointed by police as being possible members of the cell.

Police have identified his remains amid the rubble of the August 16 explosion that destroyed the house in Alcanar.

Police found in the house more than 100 tanks of butane gas and materials to make TATP, an explosive frequently used in attacks by Islamic State militants.

The group has claimed responsibility for both attacks on pedestrians - one on Thursday by a van that mowed down people on Barcelona's Las Ramblas promenade and another early on Friday in Cambrils.

The attacks and a bloody getaway in which a man was stabbed to death left 15 dead and more than 120 wounded.

Houli Chemlal, the only survivor of the Alcanar blast, told the court on Tuesday he is alive because he was on the ground floor of the house washing dishes after dinner.

He testified from a wheelchair without lifting his eyes up from the ground, according to the court official. He has been in hospital under guard since his arrest on Thursday.

The second suspect interrogated, Oukabir, testified that he did rent the vans used in the attacks on pedestrians but thought they were going to be used for a house move.

His brother Moussa was one of the five radicals shot dead on Friday by police in Cambrils.

According to another person who attended Tuesday's interrogation, Oukabir told the prosecutor that his first version of events - telling police that his documents were stolen by his brother - was something he had done out of fear.

The third suspect, Aalla, said an Audi A3 used in last week's attack in Cambrils was registered under his name but used by another sibling, according to the Spanish judicial official.

Police say one of Aalla's younger brothers died in Cambrils and another one is believed to be the second casualty in the Alcanar house blast where the imam died.

The last surviving suspect, El Karib, the owner of a cyber cafe in Ripoll, told the judge on Tuesday that he was only trying to make a profit when he bought at least two plane tickets for two alleged members of the cell.

Police later on Tuesday raided that cyber cafe in Ripoll as well as a house in Vilafranca del Penedes, searching for more evidence.

The lone fugitive from the cell - 22-year-old Younes Abouyaaqoub - was shot dead on Monday west of Barcelona after a massive manhunt. Police say he flashed what turned out to be a fake suicide belt at two officers who confronted him in a vineyard.

Police said they had "scientific evidence" that Abouyaaqoub drove the van through Barcelona's crowded Las Ramblas promenade and that he hijacked a car and fatally stabbed its driver while making his getaway.

Update - 6.50pm: A man accused of being involved in the terror attacks in Spain has told a court a bigger attack was planned, according to judicial sources.

Mohamed Houli Chemlal, an alleged member of the terror cell that orchestrated the attacks, reportedly confessed to police and a judge under questioning in Madrid.

Chemlal was detained after being injured in an explosion at a bomb factory that police believe preceded the attacks.

The explosion killed an imam who is thought to have radicalised the other suspects. Police have previously said that they believed bombs were being prepared for "one or more attacks in Barcelona."

Earlier: Four alleged members of a terror cell accused of killing 15 people in attacks in Spain are being interrogated in court, a day after the last missing member of the group was shot dead by police near Barcelona.

The four men were arrested last week for their alleged involvement in the planning or execution of attacks in Barcelona on Thursday and the north-eastern resort town of Cambrils early on Friday.

They are giving evidence in Madrid before National Court Judge Fernando Andreu, who will decide whether they should be jailed or released.

Spanish media have named the suspects as Driss Oukabir, Mohammed Aalla, Salh el Karib and Mohamed Houli Chemlal.

Chemlal, 21, was arrested in eastern Spain last week. He was the lone survivor of a blast that destroyed a house in Alcanar, where police believe the cell was preparing explosives.

More than 100 tanks of butane gas and materials to make TATP explosive were found at the house, police said.

Chemlal's evidence is considered key to understanding the motivations of the 12-man cell that killed 15 people and wounded more than 120 in the two vehicle attacks

Oukabir, Aalla and el Karib were arrested on Thursday in the north-eastern town of Ripoll.

A spokeswoman for prosecutors said the four suspects would be interrogated in the presence of lawyers provided by the court throughout the day. She said the testimony would be in Spanish without interpreters.

The lone fugitive from the cell was killed on Monday after he flashed what turned out to be a fake suicide belt at two officers who confronted him in a vineyard not far from the city he terrorised.

Police said they had "scientific evidence" that the fugitive, Younes Abouyaaqoub, 22, drove the van that barrelled through Barcelona's crowded Las Ramblas promenade, killing 13 people, then hijacked a car and fatally stabbed its driver while making his getaway.

Abouyaaqoub's brother and friends made up the rest of the 12-man cell, along with an imam who was one of two people killed in the Alcanar house.

Police said that with Abouyaaqoub's death, the group responsible for last week's fatal attacks are all dead or in custody.

Five of the 12 were shot dead by police in the seaside town of Cambrils, where a second van attack left one pedestrian dead hours after the Barcelona attack.

The Islamic State group has claimed responsibility for the Cambrils and Barcelona attacks.

Chemlal was born in Melilla, one of Spain's two North African coastal enclaves that have borders with Morocco. Spanish media say the other 11 suspects are mostly Moroccans who lived in Spain.

AP