Abstract: A filtering screen comprises a fine woven wirecloth filtering mesh (4) disposed above a coarse woven wirecloth support mesh (2). An intermediate woven wirecloth mesh (3) is disposed between the fine woven mesh (4) and the coarse woven mesh (2). the intermediate mesh (3) extending over a proportion of the area therein at outwards the rear thereof, said proportion being in the range of 20% to 40% of the area of the screen, and preferably substantially one third of the area of the screen.