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.
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The Police Federation chairman said officers were often "letting someone off with a warning and hoping for the best".
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