Catalonia’s police chief says he cannot rule out that the last suspect still believed to be at large in the Barcelona attacks may have crossed to France.

“We don’t have any specific information on this but it cannot be ruled out,” Josep Lluis Trapero told a news conference in Barcelona on Sunday, adding that border checks had been reinforced immediately after the attacks.

The revelation came as the family of seven-year-old Sydney boy Julian Cadman confirmed he died in last week’s terror attack at Las Ramblas in central Barcelona, ending days of uncertainty over his fate.

“Julian was a much loved and adored member of our family,” the family said in a statement early on Monday.

“As he was enjoying the sights of Barcelona with his mother, Julian was sadly taken from us.”

Julian’s mother Jumarie, known as Jom, was also seriously hurt in the assault after being struck by a terrorist driving a van down the world famous Spanish boulevard at high speed.

She is still being treated in a Barcelona hospital.

Search for driver intensifies

Earlier police said a manhunt was centred on Younes Abouyaaquoub, a 22-year-old Moroccan suspected of driving the van that ploughed into a packed Barcelona promenade Thursday, killing 13 people and injuring 120.

Police linked three rental vans to the main fugitive from an Islamic extremist cell that carried out deadly vehicle attacks in Barcelona and a nearby seaside resort.

A hunt continues for Younes Abouyaaquoub.

A police official says all three vans were rented using the credit card of Abouyaaquoub.

The massive manhunt for Abouyaaquoub is centred in the area around the town of Manlleu, north of Barcelona.

Abouyaaqoub, a resident of Ripoll, was reported to have frequented Manlleu, so investigators have focused there given the possibility that someone might have given refuge to the fugitive.

Abouyaaqoud’s mother took part in a rally at Ripoll town hall square on Saturday and said she repudiated the attacks, asking her son to turn himself in.

She said it was difficult for her to believe that her son was a member of the terror cell.

A cousin, Fatima Abouyaaqoud, said she was convinced that a local imam, Abdelbaki Es Satty, had radicalised her relative and the other local youths allegedly involved in the attacks.

Investigators also raided and searched the imam’s home in Ripoll looking for evidence and DNA samples.

Experts want to be able to verify if the religious leader, who has disappeared, is one of those killed in an explosion that rocked a house in Alcanar on Wednesday when a makeshift bomb factory blew up destroying what investigators believe was the cell’s bomb arsenal and killing at least two suspected cell members.

Biological remains belonging to three people have so far been found in the rubble, according to sources.

Even with Abouyaaquoub at large, Spanish Interior Minister Juan Ignacio Zoido declared the cell “broken” on Saturday.

In addition to the five killed by police, four were in custody and one or two were killed in a house explosion Wednesday. He said there was no new imminent threat of attack.

– AP, with ABC