High engine noise?

I have a W Reg Renault Clio 1.9 Diesel. A few weeks ago i noticed it was making what i can only describe as a god awful rumbling noise which happens from cold and as soon as I accelerate, when I am at a standstill it stops. I have also noticed my fuel consumption is higher than it used to be. Can't pinpoint specific time or event when it started but someone suggested it could be crankshaft main bearing. Noise gets louder the higher the revs i am doing.