Sources close to the scheme say that the capital's Greenwich site could lose the main development ''because the whole scheme is up in the air... Birmingham could rush in. It could be a fall-back position''.
The Greenwich project has been in trouble partly because of pre-election doubts about Labour's commitment to it. The site would be dominated by a dome created by Lord Rogers, the prominent architect and a Labour Peer.
Heritage Department ministers must make a quick decision in deciding whether to continue with the original project or order a dramatic change of direction. The review is likely to take four weeks and will raise fundamental questions about the financing, business plan, the size of the proposed dome and the type of structures that will be built in it.
The position of the exhibition designers, Imagination, is also being reconsidered. The company has been increasingly disenchanted at the lack of progress in the project by Millennium Central, the organisers, to which it has presented a series of designs for the interior of the dome which forms the centrepiece of the exhibition.
Imagination has stopped work on the scheme. A spokeswoman said: "We're standing back from the project. We're separated but not divorced. We are waiting for Millennium Central to make a decision."
However, no decision on designs will be forthcoming until after the review. A spokesman for Millennium Central said there had been no row: "Imagination had a three month contract to put forward designs and that's what they have done. We do not need to sign any contracts with them now and will not do so until it is necessary."
The review will also question whether more money should be earmarked for regional events to celebrate the millennium, rather than concentrating on London. The overall cost of the exhibition is estimated at pounds 650m of which pounds 200m will be a grant from lottery funds and a further pounds 200m has been earmarked as contingency, with around pounds 57m going to the regions.
The project needs pounds 195m from the private sector but Millennium Central says no money has yet been firmly committed, although BT and BA have both said they will support the project.
Millennium Central's business plan for the exhibition will be presented to the Millennium Commission, chaired by the Secretary of State for National Heritage, Chris Smith, when it meets on Monday.Reuse content