The addition of South African sides the Cheetahs and Southern Kings to the Guinness PRO12 is expected to be rubber-stamped in the next week when the worst kept secret in rugby is finally revealed.

Reports in South African media say a deal has been struck for the two teams to take part and there is a chance of a wider expansion into North America in the coming years as officials seek to tap into more countries to boost revenue.

The Cheetahs and Kings have been dumped by the Southern Hemispheres Super Rugby club competition for 2018 as that is scaled back from 18 to 15 sides, but the PRO12 is looking to go in the opposite direction and open up new markets.

Currently the competition features teams from Ireland, Wales, Scotland and Italy, but generates significantly less revenue that Englands Premier League and Frances Top 14.

Adding the Cheetahs and Kings will bring income from South African Rugby and new broadcast markets, with local media reporting the deal is likely to generate an extra £6million per annum, while negotiations are also underway with clubs in North America and other parts of Europe.

With revenues currently sitting at £12million pounds per year, that is a significant boost for a competition which has been held in various guises since the first edition in 2001.

"There's all sorts of potential issues with going to North America, potential issues if South Africa emerged as a realistic option, but I think what you have to do is weigh up those potential issues with the risk of doing nothing," Irish Rugby Football Union (IRFU) chief executive Philip Brown told the Irish Independent last week.

"The risk of doing nothing with the Pro 12 in the long term is the greater risk."

SA Rugby chief executive Jurie Roux is in Dublin this week to conclude the deal that will see the Cheetahs and Kings join for the 2017/18 season, with reports that the competition will be split into two seven-team pools.

South African media reported on Tuesday that two more of the country's Super Rugby franchises had expressed an interest in moving to the European competition when their contracts with the Southern Hemisphere version expire in 2020.

The long and difficult travel east and west across time zones to New Zealand, Australia, Japan and Argentina is taxing on the players and not good for television schedules, which has left the teams now looking north instead.