At the urging of police in Norway, Swedish police visited the woman at her home near Stockholm in late November to question her about the card, which was connected via a USB modem to a computer confiscated by police from Breivik's farm in Åsta, Norway, newspaper Verdens Gang (VG) reports.

The woman had bought the card, issued by Swedish telecoms provider Telia, in 2009 in connection with the purchase of a laptop computer. She was still paying for the subscription at the time of Breivik's July 22nd massacre, which claimed 77 lives.

“I do not want to comment on this," the woman told VG when questioned about the connection.

She called the situation "unreal", telling police she hadn't visited Norway in 15 years.

According to police, the woman explained that she had switched cards in 2010 after having trouble with her mobile internet connection. Her computer had also been repaired twice since she purchased it.

A Swedish telecoms expert told investigators that, while technically possible, it would have been extremely difficult for Breivik to have made a copy of the SIM card.

Norwegian prosecutor Pål-Fredrik Hjort Kraby also refused to comment on the reported SIM-card ties between Breivik and the Swedish woman, but confirmed for VG that police are continuing to go through the contents of Breivik's computers and hard drives.