A total of 20 teams contested the current World Cup in France which is due to conclude with the final between New Zealand and South Africa on Saturday (October 28).

It means four more will be added for the tournament in Australia in 2027, after approval by the World Rugby Council.

This necessitates a format change, with the current set-up of four pools of five due to be replaced by six pools of four.

The move will reduce the length of the tournament from seven weeks to six, after this year's event faced criticism for going on too long.

A round-of-16 will be added before the quarter-finals, with the top two teams in each pool and the four best third placed teams going through.

World Rugby has claimed that the move is a "historic reimagination of the competition format, window and timing" and that rest days between matches will remain the same length.

Draws for the 2027 pools will also be made "as late as possible" in order to "best reflect global competitiveness".

The draw for this year's World Cup took place in 2020 which meant three of the top six in the rankings come the tournament - South Africa, Ireland and Scotland - were all in the same pool.

"If we are to become a truly global sport, we must create greater relevance, opportunity and competitiveness to attract new fans and grow value," said World Rugby chairman Sir Bill Beaumont.

"This incredible Rugby World Cup 2023 tournament has demonstrated the passion and potential that lies beyond the top 10 or 12 nations, if we think big and think inclusive. 

"It is not acceptable to accept the status quo. 

"Not acceptable to do nothing.

"The decision to expand Rugby World Cup 2027 to 24 teams is logical and the right thing to do. 

"Underpinned by a new global calendar that increases certainty and opportunity, we are focused on raising standards, closing the gaps and creating a spectacle that fans demand to see. 

"With its love of sport and major events, Australia is the perfect place to do just that."

Sir Rod Eddington, the independent chairman of the Rugby World Cup 2027, called the expansion a "fantastic outcome".

"Importantly, the decision made by the Council will enable the Organising Committee to move ahead with certainty and finalise the hosting details for the Rugby World Cup in Australia," he said. 

"We look forward to working in partnership with the Australian Government, our state/territory Governments and Rugby Australia over the coming months to do so."

The new annual tournament will be called the Pacific Nations Cup and feature Canada, Fiji, Japan, Samoa, Tonga and the United States.

It is due to be played in August and September and feature two pools of three teams - one including the Pacific countries of Fiji, Samoa and Tonga and one made up of Japan, Canada and the US.

A finals series with all of the teams will take place every year, with Japan and the US taking turns to host.

The event means each country will play a minimum of three extra matches every year.

"We have seen at this Rugby World Cup just how the performance nations need certainty of regular access to top-level competition to be able to build, grow and deliver on the world stage," said Sir Bill. 

"This Pacific Nations Cup competition helps address that need as we look to reshape the global calendar to deliver greater opportunity, certainty and equity. 

"By 2026, these teams will have unprecedented high-level competition access." 

World Rugby chief executive Alan Gilpin added: "We are on the side of growth and this tournament is a key pillar in a wider strategy. 

"Combined with the proposed new two-division global competition model from 2026 and cross-over fixtures against high performance unions, performance unions could be playing an unprecedented number of annual fixtures from 2026.  

"Hosting the grand final in the USA every two years is at the heart of our strategy to grow rugby visibility, accessibility and relevance on the road to Rugby World Cup 2031.

"We will be making some big announcements on this in the coming months."