Newcastle will tell Craig Bellamy and Hugo Viana, who are both away on loan, to turn up for pre-season training if they have not been sold by then.
On loan at Celtic, striker Bellamy has no future at Newcastle after falling out with boss Graeme Souness, while midfielder Viana is at Sporting Lisbon.
Newcastle want to enter the Intertoto Cup and will begin training on 22 June.
Newcastle chairman Freddy Shepherd said: "They will be expected to report for training like everybody else."
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.
The Welsh striker will miss the rest of Celtic's campaign because of a hamstring injury and his long-term future has yet to be resolved.
Viana cost £8.5m when he left Sporting in the summer of
2002, but never settled in the Premiership.
The 22-year-old has enjoyed an excellent season back at the Jose Alvalade
Stadium and is wanted by manager Jose Peseiro, although Shepherd has yet to get a definitive answer from the UEFA Cup finalists as to their intentions.