The Professional Footballers' Association have confirmed Portsmouth failed to meet another deadline to pay their players but have been assured the funds will be provided by the end of the week.
The magnitude of the financial crisis at Fratton Park has been highlighted by players not being paid on the correct day three times this season.
They were due to receive their December salaries on New Years' Eve but that was put back to Tuesday - and 24 hours later there was still no money deposited for Pompey's players.
"Further to talks we are confident the wages will be paid this week to resolve the short-term position but the long-term position still needs to be resolved," said PFA chief executive Gordon Taylor.
"This is a serious situation that involves the Premier League and the PFA, as well as the concerns of supporters of the club and the players."
Paying their players has been one part of the financial problem at the club this season, with a prolonged transfer embargo looming.
The Premier League have imposed the player-registration freeze until they are happy with the club's finances and although there has been dialogue, Pompey have yet to provide sufficient assurances.
Pompey boss Avram Grant, as a result, is considering recalling David Nugent from his loan at Burnley if his options are limited.
"We are thinking about this," he said.
"In the next few days we will know. It depends on many things. But it could happen."
Pompey chief executive Peter Storrie believes the club may need to sell players to stay afloat - highlighting the importance of getting the transfer embargo lifted.
"If the way to keep this club alive is to sell a couple of players again, we will have to do that - but it will be an owner's decision," said Storrie.
"It will look doom and gloom but what is the other side of that? The other side of that is if you do not sell, then you could well be going into administration.
"The new owners have come in almost overnight and to be fair they have put a lot of money in the club.
"They thought they were in a strong position to replace bank finance and bring in a major new investor that was going to come in and be involved.
"But those two things have not happened and although they are working on doing that, time is catching up with them in terms of the debts and the money that is needed to run a Premier League football side."
If they did have their transfer embargo lifted, Pompey would need permission from FIFA to sell one of their most valuable assets in Kevin-Prince Boateng, as the Ghana midfielder has played for two teams this season already.
It is against FIFA rules to play for three clubs in a season but cases can be referred to the sport's governing body.
Jamie O'Hara's loan from Tottenham expires this month and he is willing to join another club in a short-term deal if he is not allowed to rejoin Pompey.
"If Portsmouth can't do it, maybe I'll be going somewhere else," said O'Hara.
"I've been doing well here and enjoying my football. (Spurs manager) Harry (Redknapp) doesn't want me to go back and not play, so if I can't stay at Portsmouth, maybe I'll be looking to move on."Reuse content