OSAKA (Kyodo) -- The organizer of the World Exposition in Osaka has rejected a request for more prayer rooms for Muslims and followers of other religions due to space constraints, a source close to the matter said Monday.

With only one prayer room available, which does not cater to a specific religion, there are concerns that the needs of expo visitors may not be met. Around 3.5 million people are expected to come from overseas.

While the exact capacity has not been disclosed, an association official said the room is likely to be able to accommodate only a dozen or so people.

According to the Japan Association for the 2025 World Exposition, a prayer room will be created in a rest area at the expo venue and have separate spaces for male and female visitors. Mats will also be provided for Muslims for worship.

Japan's Ministry of Economy, Trade and Industry forecasts that around 85 percent of anticipated foreign visitors will come from Asia, home to many Muslims with a custom of praying five times a day.

In January, a reporter from Indonesia, which has the world's largest Muslim population, sounded out the expo organizer about introducing mobile mosques, but a senior official of the association said there was "no space," and instead called for such rooms to be set up in individual pavilions.

In 2018, a Tokyo-based firm developed a mobile mosque using a 25-ton truck that has been modified with expanded space at the back to create a prayer space of up to 48 square meters. It can accommodate around 50 people at one time.

The vehicle is equipped with air conditioners and a generator, as well as water taps for pre-worship ablutions.

The Indonesian journalist has questioned the lack of prayer space at the expo venue given that multiple countries have pulled out from constructing their own pavilions, and said a mobile mosque could be "useful."

"Worship is indispensable for Muslims, and it is disappointing that (creating adequate prayer space) was not taken into consideration," the reporter said.