Sydney is in the middle of a minor conference boom as an army of cashed-up salespeople and doctors, most of them from Asia and Europe, flood the city's restaurants and shops.

Sydney Convention and Visitors Bureau figures show almost a quarter of a billion dollars in bookings for the year, thanks in part to a record number of so called "incentive conferences" such as the recent 13,250 delegate-Amway Asia gathering.

In all, 42,000 delegates are expected in Sydney in 2005, ensuring the boulevards of Darling Harbour will be thronging with overseas visitors all year.

Big venues such as the Sydney Convention Centre and larger hotels, including the refurbished Hilton Hotel scheduled to open later this year, are the obvious beneficiaries.

However, international delegates are also likely to explore further afield, seeking out local restaurants, shops, theatres and even zoos.

Delegates have as much as nine times the buying power of ordinary tourists, according to bureau managing director Jon Hutchison, making them a lucrative target market.

"For a start they're attending a big event so for many of them it's a tax deduction," he said. "And by and large, they're also a wealthier group."

Strong economic growth in Asia has fuelled an explosion in direct sales groups such as Amway, especially in China, where a conference in an exotic city such as Sydney is a strong incentive.

This has helped Sydney attract 17,000 incentive conference delegates this year, more than double last year's figure.