Full screen texture

Hi guys

I’m making a sniper scope and I have the following issue. The black texture with the crossgair needs to be full screen without getting stretched. It is pretty easy to place the texture in the center of the screen, but how can I ensure that it always cover the whole screen!!! Please help me with this!

Thanks in adcance

GUI.DratTexture(Rect(0,0,Screen.width,Screen.height),BgImgFile);

Thanks Minevr, it works! Just one thing, it is stretching the image to be wider that the original. Is there a way to overcome this? below is what I currently have and the scope texture is 1024 x 768

GUI.BeginGroup (Rect (0, 0, Screen.width,Screen.height));
GUI.DrawTexture(Rect(0,0,Screen.width,Screen.height),scopeTexture);
GUI.EndGroup ();

Thanks