2005 Renault Clio electrical

I was driving the car when I noticed when I press the break peddle my side and tail lights come on and my break lights flicker. When I release the break peddle the lights go out again. Then if I take the key out the ignition then put the side and tail lights on no problem but if I press the break peddle all the ignition and dash board lights start to flicker on and off constantly until I stop pressing the break peddle or switch my lights off. If I switch my lights on and start the engine then drive the car everything is ok apart from the brake lights are constantly on. Anybody any clue as to what is going on hear