Belgium has handed over Mohamed Abrini, the "man in the hat" bomber at Brussels airport last year, to France for questioning about the 2015 Paris attacks, federal prosecutors said.
Abrini was captured in Brussels in April over his suspected involvement in the March 22 Brussels attacks and the Paris killings, both of which were claimed by the Islamic State group. He also admitted to planning an attack on Tel Aviv.
"In the framework of the investigation related to the attacks in Paris on 13 November 2015, Mohamed Abrini was surrendered to the French judicial authorities for a period of one day," the prosecutor's office said in a statement.
Eric Van Der Sypt, a spokesman, told AFP that the decision is based on "mutual agreements" between the two countries.
"It's not uncommon that suspects in different cases are surrendered for one day or a few days," Van Der Sypt said.
Belgian investigators have said the Brussels airport and metro bombers who killed a total of 32 people were part of the same Brussels-based cell that orchestrated the November 2015 Paris attacks that left 130 dead.
Abrini, dubbed the "man in the hat" from images caught on security cameras, fled the airport without detonating his suitcase bomb after his accomplices Najim Laachraoui and Ibrahim El Bakraoui set off theirs, killing 16 people and themselves.
Several sources close to the Belgian-led investigation have told AFP that the three bombers targeted passengers travelling to the United States and also Jewish and perhaps Russian targets at the airport.
"That understanding has held up with later investigations, including with Abrini's alleged confession," a US law enforcement source told AFP.
US sources said they are confident the airline check-in counters for flights to the United States, Israel and Russia were targeted.
Abrini had a record as a long-time petty criminal who grew up in the troubled Molenbeek area of Brussels with Salah Abdeslam, the only survivor of the group that carried out the Paris attacks.
Nicknamed "Brioche" after his days working in a bakery, Abrini is thought to have given up training as a welder at the age of 18 before eventually gravitating towards extremism.
The Belgian of Moroccan origin was seen at a petrol station north of Paris two days before the November 13 attacks with prime suspect Abdeslam, who drove one of the vehicles used in the attacks.
Belgian authorities have charged Abrini with "participation in the activities of a terrorist group and terrorist murders" over the massacres in the French capital.
Identified as a radical Islamist by Belgian investigators, Abrini is believed to have briefly visited Syria last year and his younger brother Suleiman, 20, died there.
He was known to security services for belonging to the same cell as Abdelhamid Abaaoud, one of the organizers of the Paris attacks who opened fire on bars, restaurants and a concert hall before he died in a police shootout shortly afterwards.