Newcastle United will tell striker Craig Bellamy to turn up for pre-season training if they have not been sold by then.
On-loan at Celtic, Bellamy, 25, has no future at
After a poor season
Shepherd added: "We have contractual obligations to both Craig Bellamy and Hugo Viana, just like they have contractual obligations to us."
In February, Bellamy, 25, completed a loan move to Celtic until the end of the season after a public fall-out with Souness.
Bellamy has sent three weeks out with a hamstring strain but could return on Sunday against Hearts as Celtic look to secure the Scottish Premier League Title.