Gu Wen, an Expo visitor from Shanghai, won 50 pairs of designer shoes by Taiwanese brand Miss Sofi after she became the 400,000th guest at the Taiwan Pavilion last week.

Designer shoes, diamonds and free holidays are among the gifts being showered on unwitting Expo visitors who serendipitously mark new milestones on pavilions' guest lists.

Gu Wen, from the Chinese mainland, walked away with 50 pairs of designer shoes by Taiwanese brand Miss Sofi after she clocked in as the 400,000th guest at the Taiwan Pavilion last week.

Forty other members of the same tour group received coupons worth 500 yuan ($74) to shop at the shoe designer, one of the pavilion's main sponsors, bringing the total value of last Tuesday's giveaways to 60,000 yuan.

The pavilion, designed by CY Lee of Taipei 101 fame, is celebrating each 100,000th visitor with prizes from its sponsors, a publicity stunt that keeps them in the limelight and its guests lining up in anticipation of free luxury goods.

"The aim is to give our sponsors more publicity," said pavilion spokesman Wang Xianhui. "It's quite a milestone for us to celebrate 400,000 visitors today (last Tuesday) because we offer a small but refined service."

As commercial activities are outlawed at World Expos, this is one way countries can circumvent the red tape and placate sponsors, large numbers of whom have ploughed millions of dollars into supporting their national pavilions.

Many Expo pavilions have been getting in on the prize-giveaway act on varying scales, with gifts ranging from free LCD TVs to perfumes and romantic getaways in the tropics.

A recent trend has seen guests who dine at pavilion restaurants earn a free pass to see their exhibitions - meaning visitors can skip the queue by giving the restaurant operator more business. Others, such as Germany, have refused to do this on the basis of fair play.

Last month, Taiwan gave away two round-trip economy class tickets from anywhere in the Chinese mainland to the party accompanying its 300,000th visitor, a gesture facilitated by sponsor China Airlines, Taiwan's flagship carrier. The pavilion's 100,000th visitor got a 52-inch LCD TV and 200,000th got a notebook computer.

"Due to flight restrictions, most of our visitors have been unable to visit Taiwan, but we expect and hope these bans will be lifted in the near future so these people can travel there on their own," said Wang.

Taiwan, which has been receiving regular, direct flights from the mainland since 2008, is expecting 1 million mainlanders to visit this year, up 80 percent from 2009. People from the mainland can now fly to the island as part of organized travel groups but not independently.

Chile one-upped Taiwan by offering its 1 millionth guest free flights to Easter Island, a World Heritage Site in the South Pacific, and several nights' complementary stay at a resort owned by pavilion sponsor Explora. The Emirates has handed out free trips to Dubai via a lottery system.

In contrast, Argentina gave Zhou Yi, a boy from Shandong province, one of its national soccer jerseys when he pitched up as its 2 millionth visitor.

Australia, which on Monday night celebrated its 4.5 millionth guest - equivalent to the population of former Olympic host Sydney - handed its 1 millionth visitor an exclusive opal pendant worth 4,500 yuan from its gift store.

Female Expo employees are also in the running for prizes courtesy of a Miss Expo competition being organized by The Porterhouse bar and restaurant, affiliated to the Ireland Pavilion.