Dirie was found hours after police announced a nationwide search for Dirie Friday. She was last seen getting into a cab after a mix-up over a hotel in the early hours of Wednesday.
Arpigny said Dirie was being questioned by police about the disappearance and appeared to be in good health.
She recounted her own experiences of suffering genital mutilation as a child in the book "Desert Flower," which became an international best-seller.
She wrote three sequels, "Desert Dawn," "Desert Children" and "Nomad's Daughter," and served as a U.N. goodwill ambassador to fight the practice.
"There are millions of children - young, hopeless, desperate - who need help, a voice, somebody, somewhere," she told The Associated Press in a 2005 interview.
Dirie was due to speak to two conferences on women's rights organized by the European Union in Brussels this week, including one Thursday attended by Secretary of State Condoleezza Rice.
Dirie's disappearance came a week after French police said they'd found the body of another former model of African origin who had campaigned against female genital mutilation.
2Guinean-born Katoucha Niane's body was found floating in the Seine River in Paris. French police said an autopsy showed no signs of foul play, pointing to the possibility that the 47-year-old Niane may have fallen accidentally into the river.
Dirie's manager, Walter Lutschinger, said in a telephone interview that his client had been involved in an altercation in a hotel reception after a taxi driver had taken her to the wrong branch of the Sofitel hotel chain after a visit to a night club. The police were called and drove Dirie around Brussels looking for the correct hotel, after she had she apparently forgotten where she was staying.
At one hotel, while staff and police were checking for her name on a computer, Dirie walked out and climbed into a taxi that drove away, Lutschinger said police told him.
He said hotel staff told him Dirie had said she was going to buy cigarettes before getting into the vehicle.
Lutschinger said he thought she was carrying little money and no identification documents or cell phone when she vanished.
EU officials said they had expressed concern when she did not show up Thursday at the conference and had been in touch with the police.
Dirie was due to travel to the Netherlands to receive an award for her campaigning Friday in the town of Kerkrade.
By Paul Ames