South Africa were backed by World Rugby as their preferred host last month, leaving rivals France and Ireland battling to make up ground prior to the secret 31-Council member vote.

The decision to recommend South Africa followed the presentation of a detailed evaluation report on the three bidders, with the country coming out on top in three of the five criteria assessed.

In the closely contested report South Africa ranked highest with 78.9 per cent, France second with 75.8 per cent and Ireland third with 72.2 per cent.

The process has been criticised by French Rugby Federation President Bernard Laporte, while Ireland's chief executive Philip Browne is understood to have written to the game's governing body for clarification.

South Africa Rugby President Mark Alexander has warned a vote against his country will be seen as a snub to them.

Alexander had led the Durban 2022 Commonwealth Games bid, but the South African city were later stripped of the event after failing to provide financial guarantees for the event.

World Rugby have repeatedly defended the process, but the views of the three bids have added an additional layer of intrigue to tomorrow’s vote.

A total of 39 votes will be on offer, with 20 required to win.

The vote will prove the highlight of World Rugby’s General Assembly in London, which began yesterday.

World Rugby President Bill Beaumont opened the Assembly by stating the organisation have achieved great changes in the past two years.

He called for the game to work together to continue to evolve and attract a new generation of players and fans.

"These are exciting, yet challenging times for rugby and sport in general," said Beaumont.

"The competition for a share of participation, viewership and engagement has never been stronger.

"As World Rugby, we must continue to innovate, be receptive to our environment and in-tune with the needs of our unions to build a stronger, better game for all.

"Over the last two years we have achieved great, historic change.

"Governance reform, eligibility reform, disciplinary process reform and, of course, a new 2020-2032 test calendar.

"These are significant advancements for a global sport.

"This week we will announce the Rugby World Cup 2023 host union, consider further reform of our governance structures promoting gender balance and a ground-breaking women's plan – key to our continued growth.

"At the heart of everything we do will be our values of integrity, solidarity, discipline, respect and passion and I will ensure that this continues to be central to our decision-making process.

"I would like to thank all the members for their continued commitment to building a stronger, better, more inclusive, thriving game for all."

It is claimed that participation in rugby grew to 8.5 million last year, with emerging markets and female participation asserted to have been the reason for the growth.

World Rugby claim their fanbase has grown by 28 per cent to 338 million since 2013 according to recent research.

Beaumont, who was elected in 2016 alongside vice-chairman Agustín Pichot, claims the federation has accelerated change during his 18 months in charge.

"My mission continues to be to strengthen our unions, increase our global footprint and ensure that our values continue to be at the heart of our decision-making processes," he said.

"Collectively we need to always be looking to the future and work together to ensure that World Rugby strengthens its position as the voice of rugby for rugby, working in partnership with our regions and unions to ensure that we are not just a good federation, but a great federation that has integrity, inclusivity and player welfare at heart.”