It is reported that Abdelbaki es Satty is the ringleader of the terror cell and is responsible for directing the terrorists to commit the attacks in Spain which killed 14 people.

Es Satty was reportedly last seen on Tuesday and is said to be about 40 years old, but one line of inquiry being pursued by police is that he may have been killed in an explosion in Alcanar on Wednesday night.

His flatmate told newspaper La Vanguardia that es Satty left his home on Tuesday because he was going to Morocco, and did not hear from him again.

A mattress on the floor of the flat where the imam lived

A search warrant seen by Reuters confirms the flat which was raided by police belonged to a man named Abdelbaki es Satty.

He started teaching in mosques in his local area of Ripoll in 2015 and was part of the local Muslim community, but his neighbours told El Pais his teachings about Islam were not radical.

They said he taught Moroccan-dialect Arabic to children and was very reserved.

The imam reportedly taught Moroccan-dialect Arabic to children

Pictures have emerged of the inside of es Satty's flat, which show scraps of paper covered in notes strewn around, a picture of a mosque on the wall and a mattress on the living room floor.

Speaking anonymously, a police official said investigators believed es Satty might have been a second fatal victim of a botched bomb-making operation in a house south of Barcelona on Wednesday.

Emergency services had already said that one person died and another was injured in a blast that destroyed the building.

Damage caused by the explosion at a property in Alcanar. Pic: @bomberscat

Police believe the house in Alcanar was being used as a makeshift bomb factory to plan the attacks in Barcelona, possibly using large butane gas canisters in even larger-scale attacks.

El Espanol said one plan may have been to drive a van packed with explosives into Gaudi's towering Sagrada Familia basilica in Barcelona.

The unfinished church is one of Spain's most visited monuments, with more than four million tourists last year.

Head of Catalonia's police, Josep Lluis Trapero, said earlier that the explosion had forced terrorists to scrap their original plan.

 Islamic literature at the flat of imam Abdelbaki Es Satty

"They were preparing one or several attacks in Barcelona and an explosion in Alcanar stopped this as they no longer had the material they needed to commit attacks of an even bigger scope," he said.

The president of the mosque where es Satty preached, Ali Yassine, said he had not seen es Satty since June when he announced he was returning to Morocco for three months.