Charlton majority shareholder Tahnoon Nimer claims he will continue as director, despite the club saying he had resigned with immediate effect.
But the Syrian businessman says he will suspend his financial backing until chairman Matt Southall is replaced.
Nimer’s position had reportedly become “untenable” after he and Southall made claims about each other’s conduct.
Nimer is part of a consortium that took over the Addicks from controversial owner Roland Duchatelet in January.
The English Football League said developments at The Valley were “concerning” and the media comments “unhelpful”.
It also confirmed the Championship club were under a transfer embargo as the new owners had not provided evidence they could fund them until June 2021 as part of the EFL’s Owners’ and Directors’ Test.
The boardroom dispute spilled out to social media on Monday with Abu Dhabi-based Nimer posting a series of claims on his Instagram account about why he was withdrawing his investment in Charlton.
Nimer later deleted the posts while Southall issued a lengthy club statement claiming Nimer had failed to invest “a single penny of the promised funds” since January.
“Following the events of 9 March, his position is now untenable and the board has no option but to accept his resignation,” Southall said in a new statement on Tuesday.
“The board of Charlton Athletic and the senior management team will continue to run the club with its best long-term interests at heart.”
However, in a further post on Instagram on Tuesday, Nimer said: “It is now clear that our interest and the current chairman’s, with regards to the club’s future are different and irreconcilable.
“We will shortly take the necessary measures to remove the persons responsible from the club and appoint a new chairman to lead the club.”
The Addicks are third from bottom in the Championship, two points adrift of safety and on a run of three successive defeats.
Louis Mendez – BBC Radio London
What this means for the future of Charlton is extremely unclear.
Tahnoon Nimer was set to be the major money man behind East Street Investment’s takeover. His falling out with Matt Southall will raise questions as to who will now fund the operating costs at The Valley.
Former owner Roland Duchatelet, whose chaotic six-year tenure was punctuated by unrest and protest amongst the supporters, still owns the club’s stadium and training ground.
ESI said a deal had been agreed for their purchases of those assets within six months of their takeover – but now without Nimer’s funding it is unclear how the remaining directors can come close to affording the costs without new investment. Would any new investor want to take on the running costs of the club without ownership of the main assets?
Southall claimed in an email to staff that the club is still solvent – but that surely won’t be the case for long without further backing.