Sweden's security service says it is "working to assess information" after Swedish media reported that Iraqi authorities had told the agency about a group of men said to be planning a terror attack in the capital.

The Expressen daily said Iraqi authorities had informed Swedes that "seven or eight terrorists" from the Islamic State group had traveled to Sweden. The daily, quoting unidentified sources, added that the security service, known as SAPO, had sent people to Iraq to obtain more information.

In a statement on its website, SAPO said Tuesday action had been taken but didn't elaborate.

The agency added that it "quite often" gets this type of information, adding that it does not affect the terror threat assessment that "remains at an elevated level."