The leadership of the regular FLN forces based in Tunisia and Morocco ("externals"), including Ben Bella, knew the conference was taking place but by chance or design on the part of the "internals" were unable to attend. In October 1956, the French Air Force intercepted a Moroccan DC-3 bound for Tunis, carrying Ahmed Ben Bella, Mohammed Boudiaf, Mohamed Khider and Hocine Aït Ahmed, and forced it to land in Algiers. Lacoste had the FLN external political leaders arrested and imprisoned for the duration of the war. This action caused the remaining rebel leaders to harden their stance. France opposed Egyptian President Gamal Abdel Nasser's material and political assistance to the FLN, which some French analysts believed was the revolution's main sustenance. This attitude was a factor in persuading France to participate in the November 1956 British attempt to seize the Suez Canal during the Suez Crisis. During 1957, support for the FLN weakened as the breach between the internals and externals widened. To halt the drift, the FLN expanded its executive committee to include Abbas, as well as imprisoned political leaders such as Ben Bella. It also convinced communist and Arab members of the United Nations (UN) to put diplomatic pressure on the French government to negotiate a cease-fire. In 1957, it became common knowledge in France that the French Army was routinely using torture to extract information from suspected FLN members. Hubert Beuve-Méry, the editor of "Le Monde", declared in an edition on 13 March 1957: "From now on, Frenchman must know that they don't have the right to condemn in the same terms as ten years ago the destruction of Oradour and the torture by the Gestapo." Another case that attracted much media attention was the murder of Maurice Audin, a Communist mathematics professor at the University of Algiers and a suspected FLN member whom the French Army arrested in June 1957. Audin was tortured and killed and his body was never found. As Audin was French rather than Algerian, his "disappearance" while in the custody of the French Army led to the case becoming a "cause célèbre" as his widow aided by the historian Pierre Vidal-Naquet determinedly sought to have the men responsible for her husband's death prosecuted. Existentialist writer, philosopher and playwright Albert Camus, native of Algiers, tried unsuccessfully to persuade both sides to at least leave civilians alone, writing editorials against the use of torture in "Combat" newspaper.