World Rugby chief Brett Gosper flagged concerns over the news that private equity firm CVC Capital Partners is on the brink of paying more than £300 million for a stake in the Six Nations.
The Times reported that CVC, which bought a minority stake in the English Premiership last December, has agreed in principle to buy a 15% share in the commercial arm of the Six Nations.
According to the report, the Six Nations unions - England, Ireland, Scotland, Wales, Italy and France - have decided to pool their business into one commercial entity, meaning CVC will also have a share of their autumn and summer internationals.
World Rugby chief executive Gosper said that while he did not know enough about the deal to make a final judgment on whether it was "good or bad" for the game, he had his reservations.
"We would want to make sure that, for the right reasons, our influence wasn't usurped," he told a news conference.
"The areas that would concern you is that, when you have a high funding commercial owner of the sport, certain calls might be made in the commercialisation of the sport that we might not think are in the interests of the sport, either in the growth of it, player welfare or other areas.
"But many of our biggest members have welcomed this increased funding, so we can only recognise it as a positive. We just have a couple of concerns and I'm sure we'll have a chance to discuss this with CVC and the Six Nations."
World Rugby's proposal to create its own vehicle to attract major investment in the sport via a World League involving both Six Nations and Rugby Championship teams New Zealand, Australia, South Africa and Argentina was knocked back earlier this year.
"Six Nations have decided to take another route," Gosper said.
"Certainly as big an investor in the sport as a private equity firm such as CVC would create influence, and that could be in some areas that could concern us. So we need to know from CVC exactly what their medium- to long-term plans are and from that we can react," he said.
Gosper added that World Rugby had held discussions with CVC and said to do otherwise with a firm so heavily invested in the game would be "madness".
"We all want a healthy growing sport, we probably come at it from slightly different angles, but it's good to get together to ensure what we're all doing is for the good of the sport," the Australian said.