PARIS — French troops in Mali have arrested a French citizen who converted to Islam, took on the jihadist cause and threatened his native country in a video last fall, the military spokesman said Tuesday.

Col. Thierry Burkhard said Gilles Le Guen was arrested this week north of Timbuktu, the fabled city in Mali's northern desert that had been his base for some two years.

Le Guen, a former merchant marine from France's western Brittany region, was arrested overnight Sunday and was being interrogated by his French captors. He would be turned over shortly to Malian authorities, who can then decide whether to expel him to France, Burkhard said by telephone.

"We captured a French terrorist," Burkhard said.

Le Guen, thought to be in his 40s, is well known to the French. He appeared in an online video in October wearing a black turban with an assault rifle at his side, threatening France if it intervened in Mali to chase out religious radicals. He had flaunted his radicalism while living in Timbuktu, where residents said he had a wife and two children.

"I am following the road traced by Osama bin Laden," Le Guen said in a telephone interview with the French newsmagazine L'Express in January, days before the French intervention began.

Al Qaeda in the Islamic Maghreb, an Algeria-based al Qaeda offshoot, began moving into Mali's vast north a decade ago. Two other groups made up mainly of Malians joined the Algerian jihadist group, known as AQIM, and took over the north, controlling major cities and imposing strict Shariah law, like cutting the hands of thieves. AQIM is holding at least five French hostages. Other groups are holding hostages as well.

President Francois Hollande ordered a surprise French intervention in Mali in January to stop the west African country from becoming what he said was a sanctuary for terrorists that could threaten France and Europe. The first of some 4,000 troops arrived on Jan. 11. They quickly retook major cities like Timbuktu but are trying to clean out the region permanently, a task that some experts have said would be hard to achieve.

France has worried that Mali would become a magnet for Muslim radicals, particularly French citizens, or dual French-Mali nationals. It was a concern that grew with the intervention. However, only a handful of French are known to have joined the jihad in Mali. One French-Malian citizen suspected of being a scout to set up a jihadist network, Ibrahim Ouattara, was detained in Mali in November and sent to France in March. He remains in custody.

The French government also worries that French citizens hardened in battle or driven by jihad might continue their mission on home soil or spread their message to Malian immigrants in France.

The French Defense Ministry said last week that the military operation in Mali, which is now concentrated on combing the northern region to search for terrorists, has uncovered 200 tons of munitions and arms.

French forces in Mali are backed by Malian, Chadian and other African troops. France plans a staggered withdrawal with 1,000 French soldiers expected to still be in place by the year's end. UN peacekeepers are to join the troops to keep peace ahead of presidential elections that could take place as early as July.

Burkhard said that Le Guen was found "in the zone north of Timbuktu" in a desert area, but provided no further information on the location and would not say whether he was alone. He said he was being held at a French camp, but did not name the location.

Le Guen has been an unusual case among foreign jihadists, refusing to hide his presence in northern Mali.

Agaly Cisse, who runs the restaurant in Timbuktu's largest hotel, said recently that Le Guen lived mostly off of wire transfers from his family in Europe, and did odd jobs, especially technical and mechanical work, like fixing cars and broken water pumps.

One of the notables of Timbuktu, Diadie Hamadoun Maiga, who was appointed to the crisis committee that attempted to represent the city during the 10-month-long occupation, said that although the village of Danga, where Le Guen is said to have lived, is not far from Timbuktu, people in the city only started seeing him after the jihadists invaded in the spring of 2012. Maiga said he was assigned to patrol the town, and carried a weapon. He was convinced of the jihadist ideology, said Maiga, but he endeared himself to residents by taking a firm stance against the flogging of women.

"He openly took a position against Mohamed Mossa (the head of the Islamic police) especially in regards to the brutal treatment of women," said Maiga. "He was among those who went to see the big boss, Abou Zeid, to ask for Mossa to be removed," he said, naming one of the top commanders of al Qaeda in the Islamic Maghreb and the de facto ruler of Timbuktu during the occupation. Zeid was killed in February by troops.

"Gilles Le Guen won a lot of points with us because he took our side. He openly criticized Mossa, including in speeches that he gave at the market. One day he even burst into the prison and liberated the women that had been arrested by Mohamed Mossa," Maiga said by telephone.

The French press reported widely before the intervention that Le Guen had been arrested by other jihadists. Weeks later, he was shown on TV free again.

Some question how tight he really was with the jihadists. When French forces were closing in on Timbuktu, the jihadists fled en masse, but they reportedly left Le Guen behind. It's unclear if he stayed behind by choice, or was simply abandoned.

"The jihadists gave him a car. They had stolen lots of cars in the area. And they gave him a luxury, two-cabin, 4-by-4. They also gave him two barrels of gasoline, each of 200 liters," said Maiga.

He claimed that Le Guen was caught on the road to Taoudeni, around 40 kilometres north of the city.