The Prime Minister has urged Britain to unite behind the Millennium Dome, which he said would be a "huge asset" to the country and promised to be "the most fantastic day out in the world".

Tony Blair's comments came during a speech at a business breakfast at the Royal Festival Hall in London, ahead of revealing some of the exhibits that would be on display at the controversial project being built in Greenwich.

Defending the Dome and the "superb team" involved in its realisation, Mr Blair urged the British people to ignore the critics and back the project to prove that their country is "a place for daring and a boldness, for striving for excellence".

He said it would be as exciting as Disney World, "but different" and called it a "celebration of all that is best in Britain".

The Dome project is estimated to cost �758m when built

It promised to raise between �500m and �1bn extra in terms of tourism revenue for Britain and could make the country the "envy of the world", Mr Blair told his audience, and the "eyes of the world" were on them.

"This is Britain's opportunity to greet the world with a celebration that is so bold, so beautiful, so inspiring that it embodies at once the spirit of confidence and adventure in Britain.

"This is the reason for the Millennium Experience: not a product of imagination run wild, but a huge opportunity for Britain.

"It is good for Britain, so let us seize the moment and put on something of which we and the world will be proud."

Mr Blair announced that the first four founding partners would be British Telecom, Manpower, Tesco and Sky - all making contributions of at least �12m in value to the project.

He said there would also be substantial commitment from the British Airports Authority and British Airways.

The Corporation of the City of London was also committed to "substantial backing" which would match contributions from City businesses and institutions, Mr Blair said.

"Other companies that believe they, too, are 21st century companies rising to the challenge of the new Millennium will want to join this project," he said.

"There will be a lasting legacy.It will become a national landmark. Nowhere is doing anything like it, it promises to be the most fantastic day out in the world."

However, the Prime Minister also warned that if Britain did not press ahead with the Dome, "when the eyes of the world fell on Greenwich, people would see a derelict site and a signpost in the ground reading `Britain - Year 2000. Nothing doing'."

Mr Blair said the plans for the exhibition had met the criteria laid down in June, when the Government decided to press ahead with the project.

He said it would inspire people, it would involve the whole country, it would not call on the public purse, and it would leave a lasting legacy with a structure which would become "an international landmark".