Swedish Police
The Swedish police have launched a manhunt for a suspectJonathan Nackstrand/AFP

Sweden has raised the country's terror threat level to four on a scale of five as the Swedish police launched a manhunt for a suspect "planning a terrorist act." Authorities said there was "concrete information" of a possible attack in Sweden days after the Paris killing spree.

"The man is being actively searched for and an arrest warrant has been issued for the suspect based on concrete proof. The attacks in Paris on 13 November show that Islamic State (IS) may have an increased ability to carry out even relatively complex attacks in Europe. Individuals may be inspired by these attacks," said a statement issued by Polisen, Sweden's police authority. The inputs were based on information from SAPO, the Swedish intelligence service that has also said that Sweden has a large number of people returning to the country after having participated in combat activities in Syria and Iraq.

Although the identity of the suspect has not been revealed, local media reports suggest the suspect is of Iraqi descent who may have fought in Syria. At this point, however, authorities have denied any direct link to last week's Paris attacks but said IS was definitely a potential threat. "The Islamic State group which has claimed the Paris attacks considers Sweden a legitimate target," National Centre for Terrorist Threat Assessment director Mats Sandberg told AFP.

The increased threat gains more significance for Sweden, which is also dealing with the migrant crisis facing Europe, as one of the men responsible for the Paris attacks was believed to have entered Europe as a refugee via Greece, using a fake Syrian passport that was found at the scene of the carnage. Sweden is said to have received the most refugees per capita in the EU even though it introduced temporary border controls to halt the influx of refugees.

Other European countries, including Germany that had a relaxed migrant policy, have tightened their stance post the Paris attacks. Denmark also raised its threat status in the wake of the attacks and after a suspicious bag was found at Copenhagen's Kastrup airport on Wednesday (18 November).