Agathe Habyarimana was taken into custody at her home in Courcouronnes, south of Paris, on a Rwandan warrant issued on genocide-related charges, according to the official, who was not authorized to speak publicly on the matter and could not be named.
Habyarimana is the widow of former President Juvenal Habyarimana. She had been living in Zaire, then France after being helped out of her country on April 9, 1994, by French forces based in Rwanda. France rejected her 2004 demand for political asylum, saying she was at the heart of the regime responsible for her country's genocide. In October 2009, France's Council of State refused her bid to appeal the decision.
Agathe Habyarimana's arrest came just days after President Nicolas Sarkozy, on a visit to Rwanda, said that those responsible for the killings should be found and punished, including any who might be residing in France.
"We want those responsible for the genocide to be found and punished. There is no ambiguity about it," Sarkozy said. "Are there any in France? The justice system must decide."
Some 500,000 people, mostly ethnic Tutsis but also moderate Hutus, were massacred in less than 100 days in a frenzy of killings led by radical Hutus. The genocide followed the plane crash that killed the president. Two French pilots were in the cockpit.
The killings ended when Tutsi-led rebels under current President Paul Kagame defeated the Hutu extremists in July 1994.
A French advocacy group for Rwandan genocide survivors says France is a "haven" for those who helped perpetrate the genocide, and it has filed 16 lawsuits against people living here.
Sarkozy's trip to Rwanda was the first by a French head of state in 25 years. His visit was meant to reconcile the two countries, which restored diplomatic ties in November.
Relations had been broken over a French probe into the genocide that resulted in arrest warrants for nine people close to current President Paul Kagame. With the arrest of Habyarimana's widow, seven warrants are still active.
In addition, Rwanda has alleged a French role in the genocide.
"What happened here is unacceptable. What happened here requires the international community, including France, to reflect on the errors that prevented it from foreseeing and stopping this horrible crime," Sarkozy told a news conference.
Rwanda's government and genocide survivor organizations often have accused France of training and arming the militias and former government troops who led the genocide. In 1998, a French parliamentary panel absolved France of responsibility in the slaughter.
Sarkozy has referred to "serious errors of judgment" and "a form of blindness when we didn't see the genocidal aspect of the government of the president who was assassinated."
In her bid for refugee status, Habyarimana had argued that she had no power and merely took care of her house, her children and her garden. Judges said her claim was not credible.
A commission ruled that though Habyarimana had no official government post, she had de facto authority in state affairs. It said she was "at the heart of the regime," and "therefore was among the officials who planned the Rwandan genocide."
The judges based their decision on documents and testimonies.
