South African teams Cheetahs and Southern Kings are set to join the Pro12 as early as September 2017 in a major shake-up of the competition.
The two sides are expected to be cut from Super Rugby on Friday, 7 July when governing body Sanzar reduces the size of the competition.
That will pave the way for them to join teams from Wales, Ireland, Scotland and Italy in a 14-team league.
The new format is set to start for the 2017-18 season, rather than the following year.
Meanwhile, there has also been speculation that the South African sides could play some of their home matches in the United Kingdom, with Saracens’ Allianz Park mentioned as a potential venue.
The PRO12 clashes with South Africa’s Currie Cup, which means that the defending champion Free State Cheetahs and the EP Kings – who play in the Currie Cup First Division – will be forced to field second string outfits.
SA Rugby will announce on July 7 which two South African franchises will lose their Super Rugby status.