Notice that the PST labels anti-Islamic activities as “national extremism”:
Since 2001 we have focused more heavily on countering the threat from Islamic extremists and Islamic groups. The trends are worrying, and we still believe that extreme Islamism constitutes the biggest threat to Norway. At the same time we have seen a weakening of traditional extreme right-wing groups. Recruitment numbers are down and there is a lack of prominent leadership figures, hence the community is considered to constitute a lesser threat. The Norwegian police and the PST are well informed about what’s going on within the right-wing community. Another facet of national extremism is the anti-Islamic community, which poses new challenges, something that we pointed out in the annual national threat assessment for 2011. [emphasis added]
“National extremism” — who exactly do you think they have in mind?
The Observer also sends a link to an article (in English) about the police response on the day of the attacks.