R53 oil pressure light

Hi.

I have a 2003 Mini Cooper S. After driving the car for about 10mins the oil pressure warning light will come on when at idle. It then goes out if the revs come up. Driving it further the rpm which the light comes on at increases up to 2000rpm.

If I turn the car off for even just minutes the problem goes away until I have been driving for another 10mins.

Anybody have any idea what this could be.

I'm thinking it could be the pressure relief valve maybe sticking?

Obviously I have check the oil level which is ok and also replaced with new.

Thanks