A curved belt conveyor comprising: - a conveyor belt comprising a hooking element associated with an outer periphery of the conveyor belt; - a plurality of pair of rollers guiding the hooking element of the conveyor belt; - a plurality of supporting elements placed in correspondence of the outer periphery of the conveyor belt each for supporting at least one pair of rollers, at least a holding space for the hooking element of the conveyor belt being defined among each pair of rollers and the corresponding supporting element; wherein at least one main roller of at least one pair of rollers of each supporting element is movable along a trajectory extending along a rotation axis of the main roller, also extending along a longitudinal development of a corresponding main roller shaft, between a releasing position, wherein the rollers (7, 8) are distant from each other defining a corresponding intermediate space allowing passage of the hooking element of the conveyor belt to and/or from the corresponding holding space, and a retaining position, wherein the rollers (7, 8) of the corresponding pair of rollers are close to each other so that the corresponding intermediate space does not allow the passage of the hooking element of the conveyor belt at least from the corresponding holding space through the corresponding intermediate space, and wherein the trajectory of the movement of the main roller of the corresponding pair of rollers of each supporting element between the releasing position and the retaining position is inclined with respect to a longitudinal axis of the auxiliary roller of the same pair of rollers, characterized in that the main roller of the corresponding pair of rollers of each supporting element converging to the longitudinal axis of the corresponding auxiliary roller of the same pair of rollers from the releasing position to the retaining position, in particular wherein the trajectory of the movement of the main roller of the corresponding pair of rollers of each supporting element between the releasing position and the retaining position is not a rotation or a pivotable movement around a rotational axis. - a conveyor belt comprising a hooking element associated with an outer periphery of the conveyor belt; - a plurality of pair of rollers guiding the hooking element of the conveyor belt; - a plurality of supporting elements placed in correspondence of the outer periphery of the conveyor belt each for supporting at least one pair of rollers, at least a holding space for the hooking element of the conveyor belt being defined among each pair of rollers and the corresponding supporting element; at least one main roller of at least one pair of rollers of each supporting element is movable along a trajectory extending along a rotation axis of the main roller, also extending along a longitudinal development of a corresponding main roller shaft, between a releasing position, wherein the rollers (7, 8) are distant from each other defining a corresponding intermediate space allowing passage of the hooking element of the conveyor belt to and/or from the corresponding holding space, and a retaining position, wherein the rollers (7, 8) of the corresponding pair of rollers are close to each other so that the corresponding intermediate space does not allow the passage of the hooking element of the conveyor belt at least from the corresponding holding space through the corresponding intermediate space, and wherein the trajectory of the movement of the main roller of the corresponding pair of rollers of each supporting element between the releasing position and the retaining position is inclined with respect to a longitudinal axis of the auxiliary roller of the same pair of rollers, characterized in that the main roller of the corresponding pair of rollers of each supporting element converging to the longitudinal axis of the corresponding auxiliary roller of the same pair of rollers from the releasing position to the retaining position, in particular wherein the trajectory of the movement of the main roller of the corresponding pair of rollers of each supporting element between the releasing position and the retaining position is not a rotation or a pivotable movement around a rotational axis.