The decision was taken at a Special Meeting of the International Rugby Board (IRB) Council following a recommendation from the Rugby World Cup Limited Board.
Dr Syd Millar, IRB and RWC Limited Chairman said, "Prior to RWC 2007 the IRB stated that it would review the number of participating teams for future Rugby World Cups. The reason for this review was to ensure that the tournament remains competitive and commercially attractive, that player welfare concerns are addressed and it continues to be the major promotional and financial vehicle for the continued expansion of the Game."
"The IRB is committed to developing the Game and achieving specific goals within the strategic plan which include increasing the number and competitiveness of Unions at the top level and maximising the profile, profitability and value of Rugby World Cup."
"The developing nations at Rugby World Cup 2007 have produced significantly enhanced performances since RWC 2003. This is a direct result of the global £30 million IRB strategic investment programme that was established in 2005."
"Based on this plus the likelihood that surplus revenue from Rugby World Cup 2007 will provide further funds for future investment in developing nations, the Council had no hesitation in approving the recommendation from the RWCL Board that 20 teams participate at the 2011 tournament,"
"The successful New Zealand tender bid for RWC 2011 was based on 20 teams. At the Council meeting the motion maintaining the number of teams at RWC at 20 was proposed by New Zealand Council member Graham Mourie. The IRB is very confident that the tournament will be a huge success," added Dr Millar.
