The professional league features teams from Ireland, Italy, Scotland, South Africa and Wales.

Under the terms of the agreement CVC Capital Partners have secured the 28 per cent share from Celtic Rugby DAC, the private company which runs the league.

Celtic Rugby DAC, comprised of members of the Irish, Scottish, Welsh and Italian rugby unions, will retain a 72 per cent majority share.

PRO14 say the investment, reportedly £120 millon ($145 million/€133 million), will help the league to work towards its full potential to benefit fans, players, clubs and unions.

"I am delighted that we have managed to welcome CVC into the Guinness PRO14 as our partner," said Dominic McKay, chairman of Celtic Rugby DAC and Scottish Rugby chief operating officer.

"As a Board, we have been ambitious in our outlook and have significantly developed the league in recent years.

"One of our key goals was to secure a strategic partner to help accelerate our plans and CVC bring a wealth of experience and great expertise in this regard.

"Sport, like all of society is dealing with major challenges currently that we could not have imagined just a few months ago, and it is testament to the strength of our partnership with CVC that they have committed to the game of rugby in a such a significant way.

"Their enthusiasm and commitment is a welcome vote of confidence in the future of the sport and the Guinness PRO14 as an international competition.

"Completing this partnership with CVC is testament to the hard work invested by many people who have focused to deliver a bright vision for PRO14 and enable it to realise its commercial value in the global sports market.

"We are also delighted that the Federazione Italiana Rugby has now joined Celtic Rugby DAC as a shareholder after 10 years of participation in the league.

"Alongside my PRO14 Board colleagues at the Irish, Italian, Welsh and South African rugby unions I would like to warmly welcome CVC to the Guinness PRO14."

PRO14 chief executive Marin Anayi will continue in his role and will work with CVC and the rugby unions on the execution of the commercial plan.

The unions will remain responsible for sporting and regulatory elements of the league.

PRO14 say a portion of the investment will also be held centrally for the Board to invest in further capabilities for the business and in upgrading league operations in line with its growth ambitions.

"CVC’s show of faith has been impressive and is in keeping with their proven track record of success when it comes to sports investment, including Formula 1, Moto GP and Premiership Rugby," Anayi said.

"This partnership allows all of our stakeholders to plan for a sustainable period of growth, which will benefit the fans, the players and the game.

"We are very pleased to partner with CVC, who saw us as an ambitious, fast paced and innovative organisation, situated across a number of core rugby nations that can deliver an increasing impact.

"We have been clear that we believe the Guinness PRO14 is a world-class club league, that is still in its growth phase and we are confident that it will become a major standard bearer in our sport.

"We are excited that CVC clearly shares that ambition and we look forward to working with them to deliver on the league’s promise in the years ahead."