Fahim confirmed the developments to Reuters as moves continued in London to save the 112-year-old club from going into liquidation.
Asked by Reuters whether he had resigned from his position and given away his shares, Fahim said: "Yes."
Fahim said he was unable to comment on the company's position due to lack of information.
"I can neither provide my express nor my tacit approval of the statement of affairs or the report to be submitted to the English Courts by the company," he said in the letter which was carried by Arabian Business magazine on its website.
Portsmouth's chief executive Peter Storrie told Sky Sports News on Monday that the owner, Hong Kong businessman Balram Chainrai, was exploring a new initiative to try to save the club.
"As far as general negotiations are concerned (with potential new owners) they are just about complete," Storrie said. "It is now all about proof of funds. If that is proved through bona fide banks, Mr Chainrai is in London and is prepared to push ahead and get the deal done.
"In this situation, you are always sceptical but always hopeful that this football club will survive."
Portsmouth face a winding-up petition from Britain's Revenue and Customs office in the High Court on March 1, for unpaid taxes. They club had appealed for permission to sell players in a bid to raise urgent funds but the Premier League declined their request.
In October, Fahim sold 90 percent of the club's shares to Saudi businessman Ali al Faraj. Chainrai has since become the club's fourth owner in less than a year.
