Mine also makes a nasty squeek, its when the engine has warmed up, each time the pedal gets pushed in and out. But i can only really hear it at idle.
I took it to a garage, and they suggested a new cable, but this didnt fix it. Elsewhere people have told me my clutch has gathered so much crap inside, it just needs regreesing, but im not THAT mechanically minded, and i've never got around to taking it into a garage.
I think yours may be the same, just some mud and grit or whatever inside.