A long-awaited £450m waterside development could be taken over by a foreign investor.
Developers want to build a hotel and casino on land reclaimed from Southampton's River Test.
Its current investor, KMG Capital Markets, said the Royal Pier Waterfront scheme now had "buildability concerns".
Developers RPW Southampton Ltd said it hoped the new investor would buy the rights to develop the land "within three to four months".
Project director Nick Condon said the scheme needed new funding to progress.
Southampton City Council, which owns Mayflower Park where the 14-acre extension is proposed, said it still had "confidence" in the project.
Plans to revamp the waterfront include reclaiming land from the river.
But in its latest report to shareholders, KMG said surveys of the river bed had shown "significant concerns with buildability".
The firm said a new "concrete basement structure" had been proposed to resolve issues with a deep layer of "contaminated silt".
A plan to build an extra 450 flats to make the project "viable" had been shelved following opposition from landowners, the report added.
It said increased costs, together with economic uncertainty caused by Brexit, had "caused significant impact on the value of this asset".
The council chose an initial preferred developer, Morgan Sindall Investments, in 2011.
RPW submitted an outline planning application in 2015 saying building work would start the following year.
However, the application for a "gourmet epicurean market", upmarket shops and approximately 730 flats, is yet to be approved by the council.
Council leader Simon Letts said he had recently held meetings with two potential investors.
He said: "Discussions are quite advanced and I have some confidence that it will progress."