The French authorities released from custody a Norwegian extremist who was detained on suspicion of plotting a "major terrorist act".
Kristian Vikernes, 40, was detained together with his French wife on Tuesday but investigators found no evidence of a terror plot, the source said.
His wife Marie Cachet was freed .
The pair were brought in from their home in the central French region of Correze over fears Vikernes, who served 16 years in prison in Norway for stabbing a fellow musician to death, was planning an attack.
, Vikernes's lawyer Julien Freyssinet said that the Norwegian was far from preparing a terror act, describing him as a "survivalist".
Survivalism is a movement of people who actively prepare for emergencies - by for instance stockpiling food, water and medicine or building protective structures - and sometimes believe a social, political or natural catastrophe is imminent.
He said weapons seized by officers at the couple's home had been acquired "completely legally and without hiding a thing, as part of a philosophy followed by the couple - that of survivalism."
The interior ministry said at the time of the arrest that Vikernes was "close to the neo-Nazi movement" and could have been preparing a "major terrorist act".
However Interior Minister Manuel Valls later conceded no specific target or project had been identified, but authorities had decided to "act before and not afterwards."