Las Vegas-based MGM Resorts International could plow almost $10 billion into a Japanese casino via a publicly traded real estate investment trust, its chief executive has said, as Tokyo inches closer to legalizing the industry.

Casinos are currently banned in Japan, but the odds of their legalization have improved sharply thanks to political shifts that could open the world's next great frontier for high-roller gambling.

Chief Executive Officer James Murren said MGM would spend between ¥500 billion and ¥1 trillion ($4.8 billion to $9.5 billion) on an "integrated resort" — a large-scale project combining casinos with hotels, shopping and conference space — in Tokyo, Yokohama or Osaka.