Mr Blair is revealing the planned contents of the �758 million Greenwich project in an effort to win the backing of business and the public.

Can you tell what it is yet?

But critics of the dome told the BBC's Panorama programme that time is running out for a project that must include the whole of the nation.

Peter Mandelson, the minister overseeing the dome project, rejected the attacks. He said it would prove a showcase of British talent when it was completed.

Mr Blair is announcing new sponsors for the dome, along with predictions that a "huge bandwagon" of support will begin rolling.

Peter Mandelson defends the Millennium Dome (46")

The prime minister is also revealing computer graphic displays and models of exhibits including an enormous human figure planned as a centrepiece.

The government knows it must move quickly to crush growing opposition to the dome which has dogged the project since Labour came to power.

Lord Palumbo, the former head of the Arts Council, has criticised the handling of the project while its creative director, Stephen Bayley, resigned in January. He has not been replaced.

First signs of what the Dome will look like

Lord Palumbo told Panorama: "I think (the dome) could be pretty mediocre and therefore very quickly forgotten.

"Too many cooks spoil the broth and where you get a mixture of politicians, bureaucrats and creative people, you get different objectives vying for prominence.

"The thing seems to be in such a total mess."

But Mr Blair is expected to counter these criticisms and accusations that the people behind the Greenwich project still do not know what to put under the giant canopy.

Mandelson: won't let the sun go down on dome

Peter Mandelson said the dome will be a "giant mirror for the nation" reflecting a nation proud of its "ingenuity, creativity, bravery, and sense of justice and fair play."

"The Millennium is a meeting point in history. The point at which Britain, with its proud past, meets Britain, with new confidence in the future," he said.