A British citizen killed in the Stockholm truck attack has been named as Chris Bevington.

Three other people died in the atrocity, two Swedes and a Belgian national, Swedish police said.

Fifteen people were injured and 10 remain in hospital, with four in critical condition.

Swedish police have arrested a further suspect, in addition to an Uzbek man who was arrested on Friday.

"We are all devastated by the untimely and tragic death of our talented, compassionate and caring son Chris," said his father John Bevington.

"A wonderful husband, son, father, brother and close friend to many. The family requests absolute privacy at this incredibly difficult time to mourn his passing in peace."

A Foreign Office spokesperson said: "Our thoughts are with the family and all those affected at this terrible time. We will stand shoulder to shoulder with Sweden as they deal with this tragedy."

The death of a Belgian citizen was confirmed by the country's Foreign Minister, Didier Reyders, on Twitter.

"We have unfortunately have a lost a compatriot in the Stockholm attack," Mr Reyders said.

A Swedish police spokesman told a press conference: "All four deceased are now identified and family to the deceased are notified.

"There are two Swedish citizens among the deceased and there are two foreign citizens among the deceased and the countries' embassies are being contacted as we speak."

Chris Bevington
Chris Bevington was killed in the Stockholm attack Supplied

Police said the 39-year-old Uzbek man suspected of carrying out the attack was an asylum seeker who had had his application rejected. He was sympathetic to extremist groups and was being sought for deportation, officials said.

Although the suspected attacker was known to security services, he was seen as a "marginal character", Sweden's National Police Commissioner Dan Eliasson said.

Five people have been held in connection with the attack and over 500 have been questioned. A second suspect is under arrest although on a "lower degree of suspicion" than the first suspect, according to Reuters.

Meanwhile, plans are being made to move the makeshift memorial which emerged at the site soon after the attack.

Thousands of flowers left by mourners are to be moved to a nearby square because of fears an aluminum fence around the site could collapse.