A method of laser processing of a metallic material, in particular for laser cutting, drilling or welding of said material, by means of a focused laser beam having a predetermined transverse power distribution at at least one working plane (Π) of the metallic material, comprising the steps of: - providing a laser beam emitting source; - leading the laser beam emitted by said emitting source along a beam transport optical path to a working head arranged in proximity of said metallic material; - collimating the laser beam along an optical axis of propagation incident on the metallic material; - focusing said collimated laser beam in an area of a working plane (Π) of said metallic material; and - conducting said focused laser beam along a working path on the metallic material comprising a succession of working areas (T1, T2), the method comprising shaping the laser beam, wherein shaping the laser beam comprises: - reflecting said collimated beam by means of a deformable, controlled surface reflecting element having a reflecting surface with a continuous curvature including a plurality of independently movable reflection areas (200a-200r), and - controlling the arrangement of said reflection areas (200a-200r) to establish a predetermined transverse power distribution of the beam at at least one working plane (Π) of the metallic material as a function of the area of the current working plane (Π) and/or the current direction of the working path on the metallic material, characterised in that the method further comprises the steps of: - delivering a flow of assist gas towards said area of the working plane (Π) of the metallic material along an axis of the assist gas flow, - when the predetermined working path on the metallic material varies from a first to a second working direction (T1; T2), controlling the relative translation of said axis of the assist gas flow according to intermediate directions along a predetermined fitting curve between said first and second working direction (T1; T2), wherein said fitting curve has a distance from the predetermined working path not greater than the radius of the delivering area (G1, G2, G3, G4) of said flow; - detecting the current position of the axis of the assist gas flow; and - automatically adjusting the position of the optical axis of propagation of the laser beam as a function of the detected current position and/or of the detected current translation direction of the axis of the assist gas flow so as to maintain the optical axis of propagation of the laser beam directed along said predetermined working path, wherein the arrangement of said reflection areas (200a-200r) is controlled to establish said position of the optical axis of propagation of the laser beam in an area of the working plane (Π) on the metallic material comprised in a predetermined neighborhood around the axis of the assist gas flow and within a delivering zone (G1, G2, G3, G4) of said flow. - providing a laser beam emitting source; - leading the laser beam emitted by said emitting source along a beam transport optical path to a working head arranged in proximity of said metallic material; - collimating the laser beam along an optical axis of propagation incident on the metallic material; - focusing said collimated laser beam in an area of a working plane (Π) of said metallic material; and - conducting said focused laser beam along a working path on the metallic material comprising a succession of working areas (T1, T2), - reflecting said collimated beam by means of a deformable, controlled surface reflecting element having a reflecting surface with a continuous curvature including a plurality of independently movable reflection areas (200a-200r), and - controlling the arrangement of said reflection areas (200a-200r) to establish a predetermined transverse power distribution of the beam at at least one working plane (Π) of the metallic material as a function of the area of the current working plane (Π) and/or the current direction of the working path on the metallic material, characterised in that the method further comprises the steps of: - delivering a flow of assist gas towards said area of the working plane (Π) of the metallic material along an axis of the assist gas flow, - when the predetermined working path on the metallic material varies from a first to a second working direction (T1; T2), controlling the relative translation of said axis of the assist gas flow according to intermediate directions along a predetermined fitting curve between said first and second working direction (T1; T2), wherein said fitting curve has a distance from the predetermined working path not greater than the radius of the delivering area (G1, G2, G3, G4) of said flow; - detecting the current position of the axis of the assist gas flow; and - automatically adjusting the position of the optical axis of propagation of the laser beam as a function of the detected current position and/or of the detected current translation direction of the axis of the assist gas flow so as to maintain the optical axis of propagation of the laser beam directed along said predetermined working path, wherein the arrangement of said reflection areas (200a-200r) is controlled to establish said position of the optical axis of propagation of the laser beam in an area of the working plane (Π) on the metallic material comprised in a predetermined neighborhood around the axis of the assist gas flow and within a delivering zone (G1, G2, G3, G4) of said flow.