The head of the Professional Footballers' Association Maheta Molango has called the situation at Sheffield Wednesday "shocking" and "not tolerable".
Players and staff were not paid on time or in full in either May or June and owner Dejphon Chansiri is under pressure to sell the club.
Players under contract with the Championship side could now look to terminate their deals, with the club being in breach of their obligations.
"The standard contract foresees certain kinds of situations where you can terminate your contract and this is where there is a serious and/or persistent breach. So that's what we'll be looking at," Molango said.
"We've been in touch with the players. Our role is not to tell them what they need to do, [it is] to give them the tools and say, 'this is what you could do if those criteria are met'.
"Then it is for them to assess what they want to do, because I wouldn't take it for granted that just because certain criteria are met, automatically someone just terminates their contract. There are other considerations.
"We are in touch with them, it's not an easy situation as you can imagine, because ultimately, you know, people need to be paid.
"Particularly for me it's a bit shocking because normally this is stuff you see in other countries I have played in, but not in England.
"So we really want to be strong on that, and this is something that we will not tolerate and we will be very much on top of it."
The Owls, who finished 12th in the Championship last season, have already been handed restrictions over spending for the next three transfer windows as a result of the payment issues.
The restrictions will prevent the club from carrying out any transfers or loans which involve a fee for this summer's window and the two in 2026.
That restriction is currently running alongside their registration embargo which was imposed earlier in June, preventing the club from signing any new players, even free transfers, until they have paid outstanding wages in full.
