NAIROBI, Kenya -- The Norwegian police said on Thursday that it was investigating whether a Norwegian citizen was involved in the deadly siege of the Westgate shopping mall here in late September.
The Police Security Service said in a statement that it had "received information indicating that a Norwegian citizen of Somali origin allegedly was involved in the planning and execution of the attack." The service said it had sent investigators to Nairobi to work with the Kenyan police and security services in their inquiry into the attack, in which Islamist militants stormed the mall and killed more than 60 men, women and children.
The Shabab, a militant group based in Somalia, claimed responsibility for the attack. Western security officials have been deeply worried about members of the Somali diaspora who have trained and fought for the Shabab, fearing that they could return to the West and mount attacks there.
"We have lately seen an increase in the number of persons leaving Norway to take part in acts of war, attend training camps or join terrorist networks abroad," the Norwegian authorities said. "We are concerned that this development may have an increasingly negative impact on the threat situation in Norway."
Dozens of American citizens have fought for the Shabab, and there have been unsubstantiated reports that one of the mall attackers may have been American. Kenyan officials are worried about the number of Kenyan citizens among the militants.
East African militant networks extend as far as Burundi and Chad. The Tanzanian police said on Monday that they had arrested 11 people suspected of training with the Shabab, according to The Citizen, a Tanzanian newspaper.
Many questions about the mall siege remain unanswered nearly three weeks after it ended. Investigators have not yet made clear how many assailants were involved or what countries they came from. Kenyan officials have said publicly that as few as 4 or as many as 15 militants may have been involved.
The Kenyan authorities identified one assailant as Sudanese. But Col. Al-Sawarmi Khalid Sa'ad, a spokesman for the Sudanese armed forces, told the SUNA news agency in his country on Wednesday that the assailant "was of Somali origin and has no connection to Sudan," despite having the surname al-Sudani.
The TV2 television channel in Norway reported this week that Abdikadir Mohamed Abdikadir, the senior Shabab leader known as Ikrima, lived in Norway for several years. The channel said he moved to Norway in 2004 and applied for asylum. He then traveled between Somalia and Norway several times, it said, and left Norway for good in 2008 before his asylum application was completed.
American officials say Mr. Abdikadir is a top planner of attacks for the Shabab. American Navy SEAL commandos raided a villa in the Somali port city of Barawe early Saturday in a failed attempt to capture him.
The Norwegian newspaper Verdens Gang reported on Thursday that the person the Norwegian authorities are investigating as a possible mall assailant is not Mr. Abdikadir, but rather someone who was raised and went to school in Norway. The newspaper did not name the suspect. NRK, the state broadcaster, said the man was in his 20s and "grew up in Norway."
"The main purpose of the investigation is to contribute to preventing possible new terrorist actions and to investigate whether, and to which extent, the named Norwegian was involved in the attack," the police security service said.
Henrik Pryser Libell contributed reporting from Oslo, Norway, and Isma'il Kushkush from Khartoum, Sudan.
This article originally appeared in The New York Times. First Published October 10, 2013 2:01 PM