The clubs are aiming to secure a significantly reduced pay deal amid the fallout of the COVID-19 pandemic - which has seen a renegotiated Fox Sports broadcast agreement and a loss of league and club revenues.

But the clubs' offer, put to the players in a league-wide vote by their union, was rejected on Tuesday.

The Professional Footballers Australia said the clubs' proposal would allow them to "unilaterally impose salary reductions on players, with the players' only recourse to reject such a reduction being to terminate their employment" and would prevent players negotiating any reductions "in a fair and adequate manner."

PFA co-chief executive Beau Busch said the union had tabled two alternative proposals to the clubs' offer.

"At a time when the preservation of the A-League has required unprecedented sacrifices on the part of the players, they have been forced to defend their most basic contractual rights," Busch said.

"Our professional game finds itself at a critical juncture and our capacity to rebuild will largely be shaped by the quality of play on the pitch.

"Ensuring contract security and the attractiveness of the players' work environment is critical; failing to do so will simply undermine any recovery efforts."

The FFA is not directly involved in the negotiations and instead considers itself a "regulator", but it has warned it will intervene if the two parties can't reach an agreement.

PFA president and Sydney FC captain Alex Wilkinson said the players were willing to continue working with the clubs to secure a new CBA.

The players had been expected to return to training later this month or in early October, with Melbourne City previously flagging an October 5 return date.

Australian Associated Press