Representatives from the five countries last week gathered in London for two days of information-sharing briefing.

"The briefing was the first step in the expression of interest phase of the process, which over the course of the next year will provide potential candidates with an opportunity to participate in the Rugby World Cup 2015 observer and comprehensive knowledge transfer programmes," World Rugby said in a statement.

The bidding process opened on May 14 with the deadline for confirmation of a union to tender set for June 2016 and the final decision to be taken on May 2017.

Rugby World Cup tournament director Alan Gilpin said: "We are delighted with the strong level of serious interest from unions and governments in Rugby World Cup 2023 at this very early stage, which highlights the enormous hosting appeal of Rugby World Cup as a low-risk, high-return economic, social and sporting driver and we welcome further dialogue as the process progresses."

After New Zealand hosted the last World Cup in 2011, it is the turn of England this year before it goes to Japan in 2019.