The total cost of building the new Wembley stadium could escalate to �660m, making it the world's most expensive sporting venue.

Wembley National Stadium Limited, which is running the project for the Football Association, is aiming to borrow �410m - far more than had been thought.

The other �250m has already been paid out by the National Lottery or pledged from the FA.

When the project was first suggested more than four years ago, the cost was estimated at �240m. For the past year, WNSL has been quoting a total bill of �475m.

More than Sydney

"As contingencies are not called upon and we make savings on construction costs, the figure is likely to come down," said WNSL spokesman Chris Palmer.

"It is a conservative business plan."

The �326.5m costs of construction compare with about �260m paid to build the Olympic Stadium in Sydney.

The Stade de France in Paris, which hosted the last World Cup final, was also around the �260m mark.

The new Wembley is planned to hold 90,000 people and include a four-star 200-bed hotel, 100,000 sq ft of office space, two banqueting halls, restaurants, a museum and numerous corporate hospitality suites.

The costs also include improvements to the local Underground station and a road building scheme.

WNSL is said to be confident it can meet the much higher interest charges such high building costs would generate in the years after the stadium opens in 2003.

It believes annual income will total �75m to �100m.

It says the final bill could be reduced to about �600m if there are no delays, spending overruns or problems with the project.

As soon as the necessary bank lending is in place, demolition work will begin on the old stadium, including the famous twin towers.