Rafa Benitez insists that Daryl Murphy will only be allowed to leave on a permanent transfer.
The 34-year-old is available this summer as the Newcastle United boss revamps his forward line for the Premier League.
The Black Cats are keeping an eye on developments and would be interested in bringing their former player back to Wearside, though he is merely one of a number of shortlisted names.
Grayson has already brought James Vaughan in to bring much needed physicality and presence to his attack, and Newcastle's desire to recoup a good portion of the £3 million they paid Ipswich last summer could be a stumbling block.
Sunderland would have been keen on a short-term deal but Newcastle are not willing to consider that.
Benitez told the Irish Examiner: "We are talking about different things in the Premier League, and we have some clubs asking about him.
“We have been chatting at training in recent days, and he knows that if a club comes in, he will go on a permanent transfer once the deal is best for him and us.
“I was really pleased with his contribution last season, not just because he played games and scored goals, but he led by example, both in the dressing room and training.
"He was a positive influence on the team.”
Murphy scored six goals last season.