For this reason, it is considered probable that the accusations that prompted the investigation came from the New Zealand government. [Laurent Fabius], in fact, promised that the French will cooperate fully with New Zealand police on the case. And [Francois Mitterrand], according to his office, sent a letter to New Zealand Prime Minister David Lange Thursday pledging "the determination of France to shed all light on the affair."
The announcement of a high-level, independent French investigation came after midnight, with the publication by the prime minister's office of an exchange of letters between Mitterrand and Fabius. Mitterrand said that in accordance with a suggestion made by Fabius he was ordering "a rigorous investigation." Fabius replied that the investigation will determine whether "French agents, services or officials were kept informed of the preparation of a criminal attack or even took part in it."
A sailboat, rented in the French South Pacific territory of New Caledonia, was seen near the Rainbow Warrior in the days before the attack. According to the New Zealand police, four Frenchmen were aboard the sailboat. There is speculation that this sailboat was used as the supply ship for the Turengues.