Michele Alliot-Marie said she did nothing wrong during her year-end holiday in Tunisia, which came just weeks before popular protests toppled the country's longtime dictator, Zine El Abidine Ben Ali.
Jean-Marc Ayrault, who heads the Socialist opposition in the French National Assembly, demanded that Alliot-Marie step down. She refused, and some lawmakers booed as she defended herself.
"I sometimes take my vacations in Tunisia, but I pay for the travel and hotels myself," she said.
Even before the report, Alliot-Marie was in the spotlight over her handling of Tunisia: She was criticized for offering French security know-how to authorities in the former French colony as they struggled to subdue anti-government protesters in the run-up to Ben Ali's ouster Jan. 14. Police led a violent crackdown on demonstrators, often opening fire at crowds.
Le Canard Enchaine, a humor newspaper also known for its investigations, reported Wednesday that Alliot-Marie, her partner and parents flew aboard a plane co-owned by Ben Ali's brother-in-law Belhassen Trabelsi from Tunisia's capital to the beach resort town of Tabarka.
Alliot-Marie told reporters that it was a former business partner of Trabelsi's, businessman Aziz Miled, who allowed the family to join him on a prescheduled flight.
She said the president's brother-in-law had forced his way into Miled's company and described him as a "victim" of the regime. She also said Miled was a long-standing friend.
In Tunisia, observers corroborated Alliot-Marie's description of Miled, saying he and many others had been forced against their will into business dealings with the president's family, which threatened them with tax hikes or legal troubles if they refused to cooperate.
The family of former First Lady Leila Trabelsi is said to have operated like a mafia, extorting money from shop owners, demanding stakes in businesses large and small, and divvying up plum concessions among themselves.
Belhassen Trabelsi reportedly arrived in Canada last week with his family. The Canadian government said he applied for refugee status in Canada, effectively blocking efforts to extradite him to the North African country.
Tunisia has issued an arrest warrant for Ben Ali, who fled to Saudi Arabia, accusing him of taking money out of the country illegally and other charges. Interpol said its Tunis bureau issued a global alert seeking the arrest of six family members, but their names have not been made public.
Bouazza Ben Bouazza in Tunisia contributed to this report.