The league have made a revised offer to players, which would see a reduced 72-game season begin on December 15, but the union will hold further discussions with player representatives after NBPA president Derek Fisher admitted the proposal "does not meet us entirely on system issues".
Further developments will be expected once the NBPA executive committee meet with their members, which they hope to do on Monday or Tuesday.
Fisher told a media conference broadcast on NBA.com: "We've had another long day and we continue to make efforts to work through a litany of issues on all the open items that it would take to close out a collective bargaining agreement."
The players had been seeking a minimum 52.5% share of teams' basketball-related income, but would accept 51% with an additional 1% going to a fund for retired player benefits. The league's previous offer gave them between 49% and 51%, but the players argued 50.2% would be the best realistic outcome under that deal.
"We came into the last couple of days looking to try to close the gap after we expressed a willingness to move off our economic split if we got some movement on six or seven key issues in the system," Fisher continued.
"We have a revised proposal from the NBA. It does not meet us entirely on the system issues that we felt were important to try to close this deal out and so we decided to end things for now and confer with our player reps over the next few days, and then we'll make decisions about our next steps.
"We still would like to continue negotiating and find a way to get a deal done, but right now it's not that time."
Should an agreement not be reached, a new offer featuring a 53-47 revenue split in team owners' favour and salary rollbacks will be issued.
NBA commissioner David Stern acknowledged: "We had another couple of intense days.
"We made a revised proposal in the context of a possibility that we could have a 72-game season starting on December 15 and we understand that the revised proposal will be presented to the board of the union on Monday, or no later than Tuesday.
"I said to Billy (Hunter, union executive director) the clock will remain stopped while he negotiates with his union and if we don't get a positive answer then the revised offer, starting at 47% and based upon a flex cap, would be our revised negotiating position.
"I appreciate the effort the executive committee have put in by being here. I don't expect them to like every aspect of our revised proposal but we await a response from the union."