A bypass turbojet including a fan wheel carrying blades and surrounded by an annular casing, the casing including an air suction mechanism sucking air from an annular clearance formed between the casing and radially outer ends of the blades of the fan wheel. The air suction mechanism includes an inlet including at least one inlet slot formed in an inside wall of the casing and connected to a suction channel extending downstream. The inlet slot of the suction mechanism is situated axially in register solely with upstream portions of chords of the blades of the fan wheel at their radially outer ends.