Scraping noise after start

I hear scraping noise as soon as I start my engine, the noise stops or is not noticable after driving for a while, even when stopped I cannot hear like before.
I noise is like metal scrapping, like a pulley brushing a metal surface.(like a disc turning with the disc surface touching a metal surface)
The noise is loud when the car is started from cold and reduces after driving for a while, the noise sometime comes back on while driving stays for some time and again reduces.
Oil level is fine, belts are fine.
please help.