Squeak coming from under car when breakes applied!

Hi Guys,

I have had a problem for the last month with my car. The strangest thing is it comes and goes. When it is dry, and you apply the break, towards the top of the lift of the break pedal, there is a loud squeaking noise from under the car. I think it is from the rear end and in the middle somewhere. However, when the car is wet there is no noise. The same squeak happens whether I use the hand break or foot break. And it is only when I release the break and my foot is nearly off the pedal!

any ideas?

Thanks!

Andy