The costs of the Expo, which will run between April and October, will be shared equally by Japan’s central government, Osaka Prefecture and City, and the business community.
NHK’s sources say the Japan Association for the 2025 World Exposition has revised its estimate owing to rising materials and labour costs.
This is the second major change to the budget. Construction costs were initially set at about $840m, but in 2020 that figure was raised to $1.25bn.
The sources say the association is continuing to analyse the costs, and add that the total could change again.
The Expo has a masterplan designed by architect Sou Fujimoto. His concept is based on a 700m-diameter wooden ring canopy, which had an estimated cost of about £230m. This is based on the traditional “nuki” technique of carpentry, similar to mortise-and-tenon joints.
An estimated 20,000 cubic metres of timber will be required to complete the structure.