The 27-year-old defender has been linked with Celtic and Rangers, with the Glasgow rivals seeking to strengthen ahead of the new season.

The Nigerian has impressed since his arrival from QPR in 2006 and is set to return for pre-season training with the rest of the squad on Monday.

No firm offers have been tabled for Shittu yet and Simpson says bids would not be welcomed.

"We have had inquiries from Premier League clubs but no offers for Danny," Simpson told BBC Sport.

"Danny is still with us and that's the way it is staying."