By Johan Sennero and Sven Nordenstam
STOCKHOLM (Reuters) - Swedish police on Thursday identified the suspect in a manhunt launched after the country raised its terror threat assessment to the highest level ever.
Security has been stepped up around possible targets such as main railway stations and the parliament.
Security services said on Wednesday they had concrete information about a possible attack on Sweden, days after the Islamist militant attacks in Paris that killed 129 people.
Pictures of the suspect, identified as Mutar Muthanna Majid, have been distributed to police around the country. Media published a grainy picture of a smiling, bearded young man dressed in dark clothing.
"That is the picture we are working with," police spokeswoman Malin Nafver said, referring any further questions about the man to security services.
Citing unidentified police sources, public service television SVT reported the suspect was of Iraqi origin and about 25-years-old. Tabloid Expressen reported Majid was a member of Islamic State.
Police raised their presence at public and strategic locations around the country as the alert went out, including sites such as government buildings, foreign embassies and some media outlets.
Five police vehicles were parked outside Stockholm's central station but the visible police presence was minimal inside the building.
Stockholm public transit authority spokesperson Christian Hoffmann said fewer people than normal were using trains and subways in the capital.
"There aren't many people on the subway - I don't recognize my Stockholm," tweeted Camilla Kvartoft, a news anchor at public television station SVT.
Gefle Dagblad, a newspaper in eastern Sweden which published a series of investigative articles about militant Islamism and received a bomb threat in September, was among newspapers to which police had deployed patrols, its publisher told Reuters.
Lena Posner Korosi, president of the council of Jewish communities in Sweden, said evening activities such as sports training for youths were canceled in Stockholm, Gothenburg and Malmo after discussions with police and security police.
On Wednesday, security police raised their assessment of the threat to Sweden by one step, to four on a scale of five - indicating a high risk of an attack.
They issued an arrest warrant for one person suspected of preparing to carry out terror crimes in Sweden.
Over the last few years, Sweden has participated in NATO missions in Afghanistan and is training Kurdish forces in Iraq, moves that have changed its traditional image of neutrality.
The last militant attack in Sweden took place in 2010 when a suicide bomber died when his bomb belt went off prematurely in central Stockholm as he was getting ready to attack a train station or department store during the Christmas shopping rush.
(Additional reporting by Simon Johnson and Violette Goarant in Stockholm and Terje Solsvik in Oslo; writing by Niklas Pollard; Editing by Alistair Scrutton)