World Rugby has called on Japan to provide assurances over the 2019 Rugby World Cup after Tokyo's National Stadium was dropped as the main venue for the tournament.

Due to increasing costs, Japan's prime minister Shinzo Abe dropped the stadium, which was due to stage the opening match, the final and a number of crucial fixtures.

Now, the governing body has called on Japanese officials to provide a new proposal that can meet the criteria.

A statement read: "World Rugby is seeking formal reassurance regarding the following key hosting criteria by the end of September in order to undertake a thorough review and analysis of the information.

"A revised detailed host venue proposal that delivers exceptional team and fan experience, maximising opportunities for fans to be a part of rugby's showcase event. A revised tournament budget with appropriate financial security."

Meanwhile, nations are preparing for this year's World Cup, which gets underway next month on UK shores.