The Day of the Jackal

Edward Fox in The Day of the Jackal
On 22 August 1962, an assassination attempt is made on the President of France General Charles de Gaulle by the militant French underground organisation OAS in anger over the French government granting independence to Algeria. As the president's motorcade passes, de Gaulle's unarmoured CitroÃ«n DS car is raked with machine-gun fire, but the entire entourage escapes without injury. Within six months, OAS leader Jean Bastien-Thiry and several other members of the plot are captured, and Bastien-Thiry is executed.
The remaining OAS leaders, now exiled in Vienna, decide to make another attempt, and hire a professional British assassin (Edward Fox), who chooses the code name "Jackal". They order several bank robberies to pay his fee: $500,000. Meanwhile, the Jackal travels to Genoa and commissions a custom-made rifle and fake identity papers. He kills the forger when the man tries to blackmail him. In Paris, he sneaks an impression of the key to a flat that overlooks the Place du 18 juin 1940.
In Rome, where the OAS team have moved, members of the French Action Service kidnap the OAS's chief clerk, Viktor Wolenski (Jean Martin). Wolenski dies under interrogation, but not before the agents have extracted some information about the plot, including the word "Jackal". The Interior Minister (Alan Badel) convenes a secret cabinet meeting of the heads of the French security forces. When asked to provide his best detective, Police Commissioner Berthier (Timothy West) recommends his deputy, Claude Lebel (Michel Lonsdale). Soon after, Lebel is given special emergency powers to conduct his investigation, which is complicated by de Gaulle's refusal to change his planned public appearances.
Colonel St. Clair (Barrie Ingham), a personal aide to the President and one of the cabinet members, discloses what the government knows to his new mistress Denise (Olga Georges-Picot), who passes this information on to her OAS contact. Meanwhile, Lebel determines that British suspect Charles Calthrop may be travelling under the name Paul Oliver Duggan, who died as a child, and has entered France.
Although he is told the authorities know about the plot, the Jackal carries on. He seduces the aristocratic Colette de Montpellier (Delphine Seyrig). Just before Lebel and his men arrive, the Jackal escapes and drives to Madame de Montpellier's country estate. After sleeping with her again and discovering that the police have talked to her, he strangles her. The Jackal then assumes the identity of a bespectacled Danish schoolteacher named Per Lundquist. He drives to the railway station and catches a train for Paris.
After Madame de Montpellier's body is discovered and her car recovered at the railway station, Lebel initiates an open manhunt, no longer hindered by secrecy concerns. The Jackal allows himself to be picked up at a Turkish bathhouse and taken to the man's flat. The next day, the Jackal kills his host after the man learns from a television broadcast that "Lundquist" is wanted for murder.
At a meeting with the Interior Minister's cabinet, Lebel states his belief that the Jackal will attempt to shoot de Gaulle three days later on Liberation Day, during a ceremony honouring members of the French Resistance. Later, Lebel plays a recording of a phone call, in which St. Clair's mistress gives information to her OAS contact. St. Clair leaves the meeting. Denise returns to St. Clair's apartment to find that he has killed himself and that the police are waiting for her.
On Liberation Day, the Jackal, disguised as an elderly veteran amputee, enters the building he had chosen earlier. He assembles his rifle, disguised as one of his crutches, and waits at a window in an upper apartment. When Lebel finds out a policeman allowed a man to pass through the cordon, the two race to the building. As de Gaulle presents the first medal, the Jackal shoots, but misses when the tall president leans down to kiss the recipient on the cheek. Lebel and the policeman burst in. The Jackal shoots the policeman, but Lebel kills him.

Question: who kidnaped the OAS's chief clerk?
Answer: French Action Service.