MADRID — A suspected member of the terror cell that unleashed carnage in Spain last week admitted to a judge on Tuesday that the jihadists had planned to hit monuments in an even bigger attack.

Mohamed Houli Chemlal, 21, said he knew of the plans two months ago, as he, and three other suspects, appeared in court for the first time following twin attacks that killed 15 people and wounded more than 100.

The four are the only surviving suspects from what was believed to be a 12-man terror cell that rammed a van into pedestrians on a tourist-packed boulevard in Barcelona on Thursday. Hours later, members of the the group carried out a similar attack in Cambrils further south.

After a full day hearing before the judge, Chemlal and another suspect, Driss Oukabir, 27, were remanded in custody and charged with terror related offences.

But the third man who owns the car used in Cambrils, Mohamed Aallaa, was granted conditional release, with the judge saying evidence against him was weak.

The judge gave himself three more days to decide if the fourth suspect, Salh El Karib -- who manages a store that allows people to make calls abroad -- should be remanded or released from custody.

Chemlal, a Spaniard, told the judge that the cell was planning "an attack on an even greater scale, targeting monuments" using bombs, a judicial source said.

He had known of the plans for an attack "at least two months ago", he added.

’Imam wanted to blow himself up’

Chemlal was injured in an accidental explosion at the group’s makeshift bomb factory on Wednesday evening. One of those killed in the blast was an imam, Abdelbaki Es Satty, who is thought to have radicalised him and other young suspects.

He had only survived because he was out on the porch when the blast occurred, the judicial source said.

Chemlal, dressed in hospital pyjamas and with his right hand bandaged, was brought in after a doctor determined he was fit for interrogation, a court spokesman said.

While Chemlal told the judge the imam had wanted to blow himself up, two other suspects "blamed the imam for the plot while another two denied knowing him", the source added.

Earlier, police had revealed that the suspected jihadists had been preparing bombs for "one or more attacks in Barcelona".

Josep Lluis Trapero, head of police in Catalonia, said 120 gas canisters and traces of TATP components -- a homemade explosive that is a hallmark of the Islamic State group that claimed the attacks -- had been found at their bomb factory.

The accidental explosion in the house in Alcanar, south of Barcelona, forced the suspects to alter their plans.

The victims of the attacks were from three dozen countries, including Australia, China and the United States. — AFP