The Evening Chronicle says Sterry and Colback were both left out of Newcastle's squad for the season last August and may have hoped to be included in the latest roster for the final games of the campaign.
However, the duo have been asked not to visit the training ground as the club looks to limit the number of people on site due to health and safety.
And it means Sterry and Colback are all but free to start looking for new clubs.
Colback was set to miss the rest of the season after damaging his medial ligament in training in January.
While the report says Sterry is attracting interest from lower league clubs.