As Osaka moves forward with plans to build an integrated resort complex in the hope that the Diet will soon legalize casinos, the future role of the Universal Studios Japan theme park remains unclear.

Management is in a long-running dispute with Osaka municipal officials that appears to have resulted in a loss of trust.

Osaka Gov. Ichiro Matsui and Osaka Mayor Toru Hashimoto are confident casino gambling will become a reality and hope to make Yumeshima, an artificial island in Osaka Bay, the site of one of Japan's first integrated resorts, which would include hotels, entertainment facilities and casinos.

Officials say at least two casino operators, MGM Resorts International and Galaxy Entertainment Group, are the front-runners to win a license for an Osaka casino resort.

Meanwhile, Universal Studios Japan, whose theme park lies about 5 km from Yumeshima, has ambitions to enter the integrated resort business as well.

But Hashimoto and Matsui have reacted negatively to the idea of USJ operating a new resort. Since 2010, the city has been in and out of court to try to force USJ to pay more for city property it leases.

"I don't have a relationship based on trust with USJ's management," Hashimoto said this week.

"USJ has no experience at all in the casino sector," Matsui added.

Both officials hope an Osaka casino would attract huge numbers of foreign tourists, especially from East Asia. The number of foreigners visiting Osaka Prefecture rose to more than 2.6 million in 2013, with the increase attributed to a weaker yen and relaxed visa regulations. The number of tourists from Southeast Asia was up by two-thirds over the previous year's figure.