Police are searching the home of a Norwegian neo-Nazi for weapons and explosives, a source told Reuters.
Kristian Vikernes was arrested in France, where he now lives, after his wife bought four rifles.
"That was at the origin of the investigation ... There were several suspicions that made the services fear he could possibly carry out a violent act," a police official confirmed.
More top news
Former Girls Aloud singer Kimberley Walsh is pregnant with her second child, she has revealed.
Chancellor George Osborne will seek to reassure financial markets on Monday morning following Britain's decision to leave the EU.
In his first outing since the referendum result, the lead Leave campaigner has outlined his vision for a post-Brexit Britain.