The left-sided player has struggled to make an impression under Kevin Blackwell and spent the latter half of last year out on loan to Norwich City.

It remains to be seen how many A-League clubs decide to test the waters and make United an offer.

United have extended the contracts of both Nick Montgomery and Paddy Kenny, but Ugo Ehiogu and Danny Webber have not been offered new deals.

The Blades will also hand contract extensions to Leigh Bromby and Ian Bennett, while Lee Hendrie, Nicky Law and Zeyn S-Latef join Carney on the transfer list.

Four other players - Ben Starosta, Keith Quinn, Jamie Annerson and Maxime Chanot - have been released as manager Kevin Blackwell starts to reshape his squad.

Midfielder Montgomery and goalkeeper Kenny have been in eye-catching form for the Blades during the run-in, but veteran defender Ehiogu's season was cut short in December due to an Achilles problem, while Webber has also struggled with injury.

On-loan players Greg Halford (Sunderland), John Joe O'Toole (Watford), Arturo Lupoli (Fiorentina) and Craig Beattie (West Brom) have all returned to their parent clubs.