Stockholm attack suspect was refused residency. Picture: Swedish police.

The 39-year-old Uzbek man is suspected of having driven a truck into a department store in the city on Friday.

His application for residency was rejected in June last year and he was being sought by immigration officials, police said.

The suspect behind the Stockholm truck attack had been facing deportation and had extremist sympathies, Swedish police say.Source:Getty Images

But by February, he had “gone underground” and his case was handed over to police, police chief Jonas Hysing told reporters in Stockholm on Sunday.

A second suspect, whose identity was not disclosed, was arrested on Sunday. That person can be detained until Wednesday, at which point prosecutors would have to ask a court for permission to extend their detention.

However, Reuters news agency said the person was arrested on “a lower degree of suspicion” than the first suspect.

Security officials in neighboring Norway, where a 17-year-old asylum-seeker from Russia was detained early Sunday in connection with an explosive device found near a busy subway station, spoke of the alarming potential for a copycat effect.

Norwegian’s security agency said it wasn’t clear if the teen planned to carry out an attack with the primitive homemade device police defused without any injuries. Agency head Benedicte Bjornland said it was likely the youth had been inspired by recent attacks in Stockholm, France, Germany, Britain and Russia. “The attacks demonstrate how easy such attacks can be carried out, and prove to others that it is possible to make something similar,” Bjornland said.

People hold signs of solidarity on Sergels square after a peace demonstration on April 9, 2017 in Stockholm, Sweden. Picture: Getty.Source:Getty Images

The Stockholm attack followed a string of similar assaults in Europe using vehicles.

The deadliest came in France on the Bastille Day national holiday last July when a man rammed a truck into a crowd in the Mediterranean resort of Nice, killing 86 people.

Last month, Khalid Masood, a 52-year-old convert to Islam known to British security services, drove a car at high speed into pedestrians on London’s Westminster Bridge before launching a knife attack on a policeman guarding the parliament building.

Five people were killed in the attack, while Masood was shot dead by police. In 2010, another section of Drottninggatan was the scene of Sweden’s only other terror attack, when a suicide bomber blew himself up, slightly injuring several others