Pro12 bosses are in "advanced and positive discussions" with South African Rugby Union over the possibility of adding the Cheetahs and Southern Kings to the league following their removal from Super Rugby.
The Cheetahs and Kings were the two South African franchises chopped as part of a restructure, which will also see one Australian side - either Melbourne Rebels or Western Force - axed from the competition.
The addition of the two clubs to Pro12 has been widely anticipated and Celtic Rugby confirmed a decision on their inclusion is on the horizon.
"Celtic Rugby can confirm that advanced and positive discussions are taking place with the South African Rugby Union regarding the introduction of two teams into an expanded Guinness PRO12 Championship," a statement on the Pro12 website read.
"Given the proximity of the 2017-18 season start, a final decision on this potential expansion will be confirmed as soon as practical."
Southern Kings finished fifth in Super Rugby's South African Group, while the Cheetahs ended second bottom. The two contested their final Super Rugby encounter last week, with the Cheetahs staging a fightback to claim a 21-20 win.