Advance sales of admission tickets for the 2025 World Exposition in Osaka began Thursday, 500 days before the global event in western Japan opens, amid lingering concern over ballooning costs.

The Japan Association for the 2025 World Exposition aims to cover most of the operational costs through admission fees, setting a sales target of 23 million tickets for the event running from April 13 through Oct. 13.

Photo taken in Osaka on Nov. 27, 2023, shows a construction site for a ring-shaped wooden roof with a circumference of 2 kilometers at the site of the 2025 World Exposition to be held in the western Japan city. (Kyodo) ==Kyodo

The organizer hopes that 14 million tickets, or about 60 percent of the sales target, will be sold in advance.

Facing headwinds such as slower-than-expected progress in the building of pavilions by overseas participants due to high material and labor costs, the association is aiming to build momentum through pre-opening events.

The cost shouldered by the central and local governments and the business community to build venue facilities has swelled to up to 235 billion yen ($1.6 billion), nearly double the previous estimate.

About 30 countries have selected builders for their pavilions at the expo, but construction had not started as of Wednesday, according to a senior official of the Ministry of Economy, Trade and Industry.

The rising construction costs for pavilions prompted Mexico and Estonia to withdraw from the expo, which will be held on Yumeshima, a man-made island in Osaka Bay.

Advance tickets are cheaper than those that will be sold during the expo, with an adult one-day ticket purchased during the event priced at 7,500 yen.

Of them, opening tickets for adults, priced at 4,000 yen, will allow single entry between the opening day and April 26. The tickets are priced at 2,200 yen for visitors aged from 12 to 17 and 1,000 yen for those aged between 4 and 11.

One-day tickets for adults, priced at 6,000 yen, will allow single entry on any day through the close of the event if purchased between Thursday and Oct. 6, 2024.

Multiple-entry season and summer passes for adults are also available priced at 30,000 yen and 12,000 yen, respectively.

Supplied illustration shows the design of the venue for the 2025 World Exposition in Osaka. (Courtesy of the Japan Association for the 2025 World Exposition)(Kyodo)

Russia has also pulled out of the expo, citing a "lack of efficient communication with the host."

Chief Cabinet Secretary Hirokazu Matsuno told a press conference Wednesday that the Russian invasion of Ukraine contradicts the philosophy of the world expo, which cherishes sympathy for others and respect for diverse cultures and values.

Japan does not envisage Russian participation in the event unless the situation in Ukraine changes, he said.

The total number of participating countries and regions currently stands at around 160, with the recent addition of nine countries including Denmark and Finland, as well as nine international organizations, according to the Foreign Ministry.

Related coverage:

Russia withdraws from 2025 World Expo in Japan

Mexico, Estonia withdraw from 2025 World Expo: Japan minister

Japan OKs Osaka expo construction budget of up to 235 bil. yen