The effort by the Pompey Supporters Trust to buy its club from administration have been dealt a potentially terminal blow with the emergence of a new bid from investors led by Keith Harris, the investment banker. If his bid succeeds, Harris says he will leave his investment bank, Seymour Pierce, and become the Portsmouth chairman.

The bid's financial backers are Pascal Najadi, who Harris said is an investment banker living in Malaysia, and Alan Hitchins, who is described as "a professional investor". Harris told the Guardian the men are paying cash to buy Portsmouth, which is in administration, not borrowing the money.

"I am really excited by this; it is the best opportunity to own a football club I have seen in years, and the fans are amazing," Harris said. "This club deserves to be owned by guys who love football."

The PST will be bitterly disappointed if Harris beats its bid to take over, which the fans have worked on since last February, when the club collapsed into administration. One of its major concerns, besides the fact that it would thwart mutual supporter ownership, is that Harris's bid will, initially at least, leave Portsmouth as tenants of the ground.

Under the deal proposed to the administrator, Trevor Birch of accountants PKF, Fratton Park will be handed back to Balram Chainrai, the Hong Kong-based previous owner of Portsmouth. Chainrai's company, Portpin, still has a mortgage over the club and Fratton Park for £18.6m. The trust is offering £3m to buy the ground, and although Chainrai refused the offer, as the trust's was the only bid, PKF has been pursuing court proceedings to force Chainrai to accept it.

Harris has now agreed a deal with Chainrai for Portsmouth to rent Fratton Park from Portpin, with an option to buy it outright, which Harris said he intends to do quickly after taking ownership of the club, although he will not commit yet to a firm date.

Some Portsmouth fans also suspect there may remain close links between Harris and Chainrai, as Harris acted as the adviser when Chainrai sold Portsmouth in 2010. Harris says no formal connection exists, and that ownership under him and his investors will be independent of Chainrai.

"We will not be carrying forward any legacy issues associated with the recent past," Harris said.

PKF confirmed it has received Harris's bid: "We believe this offer is worthy of consideration and could be completed without the need for a court case," PKF said. "The administrators are charged with securing the best return for all creditors and therefore have to consider the offer."

The key difference is Harris's securing the agreement of Chainrai to his deal. Although he would not say how much his option proposes in order to buy the ground, it is clear it will be more than the £3m being offered by the trust.

PKF's court case to force Chainrai to accept the trust's offer was based on there being no alternative bid, and argued that only the trust's offer could save the club from liquidation. However, it was always vulnerable legally to another bid which Chainrai would accept.

PKF sources said Harris's bid offers more money to creditors, because it satisfies Chainrai, who will cancel the £18.6m owed to him. Harris also proposes paying players who are owed money more quickly.

Any bid will require Football League approval. The PST will argue it should be refused because their takeover remains the best for Portsmouth's future.

"Our bid is the only one which frees the club from previous regimes," said Ashley Brown, the PST chairman. "Under Keith Harris's deal, the club and ground will be separated. Ours will see Portsmouth owned democratically by supporters, and we have money to invest."

David Lampitt, the chief executive of Supporters Direct and a former Portsmouth chief executive, said: "It would be a travesty if, after all the effort put in by the supporters trust and the scale of political backing for supporter ownership, their bid loses out at this last minute."