At some point one of the starys I feed has managed to get in and leave me a nasty niff on my office carpet.

I have washed it with warm water and detergent on 5 separate occasions but I can not get rid of the smell and now I am sure the damp carpet is making it worse.

Any ideas gratefully received

Try a pet oder spray remover. You can buy them at most pet stores. This works good
http://www.justrite.com/
You can also try making a spray with baking soda and hydrogen peroxide.

I like a product called urine gone, I can tell you that it is very effective and did not damage my carpet. This product is sold at the big box stores, CVS,Walmart, K-mart etc... for about 10 dollars a bottle follow directions and it is very effective.
I have also seen seen where vinegar is said to work.

Ooh yuck. Was it regular pee or was it male cat spray? The spray, I can honestly say is the most awful scent that has ever entered my nose. Ever. Period. Anyway, in addition to the excellent suggestions already made, I've had some luck with NaturesMiracle on regular pee. I had a stray cat that I took in for a bit and he sprayed my couch. I had it professionally cleaned to no avail. So I replaced the cushions. If it's cat spray, my prayers are with you.

Thanks All.

I will start with the baking soda suggestion,move onto vingar and if the smell is still there I will look for some UK alternatives to your shop purchased sprays.

Failing that it's a new floor covering I think as I have to sit in this room nearly all day working and the smell in in my nose and throat... yukkkk