The Competition and Consumer Protection Commission has cleared an investment in the Pro14 rugby league by private equity firm CVC Capital Partners, subject to conditions relating to the Six Nations tournament.
Last year CVC Capital Partners agreed to acquire a 27% stake in Celtic Rugby DAC - which operates the Pro14 on behalf of the Irish, Scottish and Welsh rugby unions.
If completed, the deal is expected to mean a windfall of around €40m for each national union.
Following the deal's announcement in November the CCPC undertook an investigation into the acquisition, to identify whether it would lead to a lessening in competition.
During that process it became aware of media reports of another possible rugby investment by CVC, this one relating to the Six Nations Championship.
The CCPC said this "raised potential competition concerns regarding the likely competitive impact of the proposed transaction in the event of such investment."
To help allay those concerns CVC said it would voluntarily notify the CCPC if it, directly or indirectly, entered an agreement to acquire control of the commercial activities of the Six Nations.
The CCPC said this would be "appropriate and effective" in addressing the potential issues, and it has approved its investment in Celtic Ruby subject to the binding commitment.