Nepal's decade-long civil war claimed 16,000 lives and displaced 100,000 people.
The conflict was between Maoist rebels trying to overthrow the country's ruling monarch and the national army. There are allegations of human rights allegations on both sides.
The Maoists ended the conflict in 2006 under a peace deal with the government and won a general election in 2008.
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The announcement came a day after a famine was declared in two areas of South Sudan following three years of civil war and severe inflation.
It is unclear what their alleged plans were.
Anti-terror police are currently questioning the men who were arrested at three separate locations in France.