For sale: luxury apartments aboard the cruise of a lifetime. A snip at pounds 4.5m

For the men and women who have everything - a pounds 4.5m private apartment on a giant cruise liner.

Destination - the carnival in Rio, the grand prix in Monaco, and all the sassiest events in the world's social calendar.

Plans for the ship, The World of ResidenSea, feature a liner larger than the QE2 and a membership culled from the address books of the wealthy.

The idea is to create one giant floating luxury mansion block where the most affluent people can enjoy their own homes with neighbours just like themselves.

Its itinerary will include the Scandinavian fjords, the Caribbean, Mexico and New York, as well as calling at events like the Sydney Olympics in 2000.

Some unable to tear themselves away from their money-making ventures are even reported to be planning to set up business on board the 1,000ft, 85,000 ton ship which will boast a spa, tennis courts, seven restaurants and a supermarket.

"The World offers the opportunity to own a private home in the world's greatest cities and resorts, to travel the world without leaving the comfort and security of one's own home," according to Savills, the estate agent marketing the project.

Charles Weston-Baker, a Savills director, admits it is one of the more unusual sales opportunities he has handled. But he claims to have had a string of inquiries already from those wearying of the troubles of staffing and maintaining yachts or second homes in the Caribbean and Mediterranean.

"There's been a tremendous amount of interest and what's been most interesting is how serious most of those responses have been," he said yesterday.

"I've had several sales from all sorts of areas, but mostly people who run their own companies or are senior partners in law and accountancy firms."

Millionaires who balk at the pounds 4.5m price tag can take something a little smaller, starting at pounds 800,000, furnishings included. Maintenance is an extra 5 per cent per annum. A press launch at the Dorchester Hotel in Park Lane, central London today, aims to confirm the luxury image.

The liner is the brainchild of Knut Kloster Jnr, a member of the Norwegian family which is credited with starting the holiday cruise industry in the 1960s.

The $500m (nearly pounds 300m) scheme needs bookings in the bag to proceed. But it is understood that nearly a fifth of the 250 apartments have been sold and the project is close to go-ahead.

Three ship yards, thought to be in Finland, France and Germany, are in the running for the business and a contract is set to be sealed in the next couple of months, with delivery in time for the Millennium.

The only cloud on the horizon is a scheme by Mr Kloster's father for the world's biggest passenger ship. After 10 years in planning, the Phoenix is yet to rise.

One cruise industry insider said the failure of the Phoenix meant there was a certain scepticism as to whether the World could succeed.

But he added: "It could happen. The Klosters have got a good track record in cruises. They are not be scoffed at."