Mellor had failed to agree peronal terms with Sheffield Wednesday where he spent last season on loan and Phil Brown went on record as saying he would prefer the frontman to stay than go to another League One side.
The striker has one year remaining on his contract and Preston would let Mellor go due to his high wages. It now appears that Doncaster, Southampton and Watford are all interested in taking the striker.
Agreeing a fee will not be a problem as Preston had agreed a small transfer fee with Sheffield Wednesday but Mellor's wage demands may well prove to be the stumbling block once again.