The BBC's Nick Higham: "The fourteen exhibition zones are starting to take place"

Lord Falconer of Thoroton, the Cabinet Office minister in charge of the £758m attraction, said the entry prices set at £20 for a single ticket and £57 for a family of five were "extremely reasonable".

A massive sales drive for the Dome - to be opened by the Queen in a New Year's Eve ceremony - was launched by television personality Anthea Turner as she became the first person to buy a ticket to visit the event.

But Ms Turner, who bought her entry ticket from Waterloo Station, which has one of the 25,000 National Lottery terminals which will sell Dome tickets, admitted she will not attend the opening on 31 December.

Also launching the official start of ticket sales, 90 by 60ft banners were unveiled inside the Dome, with one carrying the slogan for the new advertising campaign, One Amazing Day.

Lord Falconer: "In many people's eyes the dome is the symbol of the millennium"

A target of 12 million visitors during 2000 has been set by the New Millennium Experience Company, whch is organising the exhibition. The company aims to keep the public "entertained, educated and inspired" with 14 themed zones.

Lord Falconer dismissed criticism that the pricing could exclude people on low incomes, and said the cost reflected the quality of the "incredible experience" on offer.

He told BBC Radio 4's Today programme: "As a result of no public money in this scheme, there had to be a price to go in it. The price we are charging is extremely reasonable."

But Liberal Democrat spokesman Norman Baker criticised the ticket cost, saying they were pricing the poor out of going.

"If the Millennium Dome is anything, it should be access for all and the price they are setting is effectively cutting people out and discouraging those with lower incomes from access to the Dome," he said.

The £4m advertising campaign includes a television and nationwide poster adverts telling people they can now buy tickets.

The Dome's dramatic "Body Zone"

Discounted rail fares for visitors to the Dome from Scotland, Wales and the English regions have also been announced by train operators.

Jennie Page, chief executive of the New Millennium Experience Company, said: "A visit to the Dome in 2000 is going to be an amazing day out and an unforgettable way to celebrate the millennium."