A French charity worker and a churchman were abducted on Monday in Bangui, the capital of Central African Republic, the French Foreign Ministry and the Caritas charity said.
The 67-year-old woman was working for a charity providing health and education support to Central African villages, the ministry said in a statement.
The French ambassador in Bangui is in contact with the archbishop's office in the city, which has started negotiations with the captors, it said.
Abby Elysée Guendjiandé, national secretary of Caritas, said a pickup truck carrying three people including the Frenchwoman was stopped on the northern outskirts of the capital, which is controlled by the anti-balaka militia.
The charity worker and the churchman were seized, while a third person was not taken because the militia men took him for a driver, he said.
"When we called ... (her) telephone later the kidnappers picked up and said: 'Release our General Andjilo and we will liberate the hostages,'" Guendjiandé told Reuters.
U.N. peacekeepers in Central African Republic have arrested a senior leader of the anti-balaka militia, known as General Andjilo, wanted for crimes including murder, rebellion, rape and looting, the country's senior prosecutor said on Sunday.
A spokesman for Caritas in Paris told Reuters the Frenchwoman does not work directly for Caritas but for the Catholic church's local health desk and two churchmen from the Holy Ghost congregation were in the vehicle.
Central African Republic sank into chaos when the mainly Muslim Seleka seized power in the majority Christian state in March 2013, ousting President Francois Bozize.
A backlash from the mostly Christian or animist "anti-balaka" militia led to violence that has killed thousands and displaced around 1 million people.
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