Millennium Central needs to raise pounds 150m in sponsorship to match the pounds 200m being put in from lottery funds by the Millennium Commission in order to pay for the exhibition, due to open in autumn 1999.
But a meeting of the commission tomorrow will want to be satisfied that private funds are available before giving the final go-ahead.
Millennium Central is also seeking government guarantees of its borrowing but this is provoking a row between the main political parties.
Michael Heseltine, Deputy Prime Minister and a member of the commission, is keen to press ahead regardless of any financial obstacles. He has suggested that the way round any funding difficulties is to allow the commission to continue in existence beyond the end of 2000, retaining its income of 20 per cent of lottery funds for as long as is needed to pay off any debts.
Labour, however, conscious that it may well be in government when the final bills need to be paid, refuses to give carte blanche to any over- spending. Nick Raynsford, housing spokesman and Greenwich MP, is a firm supporter of the exhibition but said: "This is not the way to go about a major project. If you do not set a limit, all the contractors will know that and try to put in for as much money as they can get out of the system."
Dr Jack Cunningham, Labour's heritage spokesman, said: "While we support the idea of the project, we want to see a proper budget before committing ourselves."
Barry Hartup, the chief executive of Millennium Central, said: "You cannot expect companies to promise all the money before they know what the exhibition is. I am confident they will come forward in the end."
The search for sponsorship was hampered by Mr Heseltine's heavy-handed approach early on, when he tried to arm- twist major companies into supporting the exhibition and alienated many potential donors amid complaints of blackmail.
The overall budget of the exhibition has been estimated at pounds 700m, with ticket sales being estimated at pounds 350m in addition to the pounds 200m of lottery money and pounds 150m sponsorship.
With 13.5 million people expected to attend over the 15-month opening period, from September 1999 to December 2000, ticket charges will range from around pounds 47 off-peak to pounds 70 for a family of four.
Mr Hartup, insists that it will not be difficult to attract such numbers. "The ideas coming from Imagination [the company designing the exhibition] are absolutely amazing and will attract everyone from children and their parents to grannies and disabled people," he said. The exhibition, in a massive dome, will have the theme of time.
While clearing contamination on the site, formerly a gasworks, has been progressing well, there are doubts about the timetable.
Ministers have admitted that the design work was delayed by the holding of a competition which in retrospect Greenwich always seemed destined to win and which now seems to have been unnecessary.
Mr Hartup admitted that the schedule was tight. "We need to understand that we have been given the full go-ahead on Wednesday," he said.
"There is no slack." Indeed, Millennium Central still has no permanent staff and Mr Hartup is on a temporary secondment from the Welsh Development Agency which runs out at the end of this month.
The future of the site also remains undecided. Mr Raynsford has been pressing to ensure that the dome has a 60-year life.
"It could then be used for sports facilities and with a new Wembley being linked by the Jubilee Line extension, it could be the basis of an Olympic bid," he said.Reuse content