What causing the sqeaky noise on my Nissan Micra 98 SI?

Hello

I have a Nissan Micra 98 SI

I've noticed over the last few weeks an intermittent squeaky noise when driving along. From the driver's seat it appears to be coming from the nearside rear.

When I start to drive the first few minutes there's nothing then when I go over an uneven road the squeaking starts and stops and then starts again.

When I drive over a smooth road it doesn't seem so loud even stopping at times.

I find this quite worrying as my MOT is due soon. However the sound is irritating

Please could someone give me some suggestions as what could be problem

Many Thanks