A corrosion resistant intruder screen has a frame including elongate frame members (3) with a mesh (4) clamped to frame members (3). The frame members (3) each have a first holding channel (50) formed therein and a clamping portion (6) spaced from the first holding channel (50). Clamping members (7) co-act with fastening means (8) to clamp the mesh (4) between the clamping members (7) and the clamping portions (6) with leveraged clamping action. The screen includes covers (54) which are configured to be clipped to the frame members (3) and which each have a second holding channel (60) formed therein. The screen further includes a sealing assembly comprising first sealing members (51) and second sealing members (61). The first sealing members (51) are supported by the first holding channel (50) in the frame members (3) and positioned against one side of the mesh (4) and the second sealing members (61) are supported by the second holding channel (60) in the covers (54) and positioned on another side of the mesh (4).