Georgia have been told the Six Nations will remain a "closed competition" for the next decade at least.
The Lelos are currently ranked two places above Italy in World Rugby's rankings, and the Azzurri's ongoing struggles in the competition have led to debate on promotion and relegation.
However, Six Nations chief executive John Feehan told the Daily Mail that organisers would not be swayed by public opinion.
"It is a closed competition, owned and controlled by the six unions concerned," he said.
"There is no vacancy. Right now we are perfectly happy that we have the six strongest teams in Europe in our competition."
Feehan added: "Are we closed to every scenario? No, but it takes a while to see a convincing argument -- 10 or 15 years.
"We have to take a good, considered view about what is right for our six unions. They would all have to agree that this is what they want.
"At this stage, talk of bringing in other teams is premature."
Feehan also insisted that World Rugby had no right to intervene in how the Six Nations is run.
"World Rugby have no input into this tournament," he said. "They have no control over it, no ownership of it. It's not theirs to tell us what to do with it.
"It is World Rugby's job to develop the game. Our job is to run the Six Nations as we see fit. Do the unions have a responsibility to help develop and expand the game? Probably, yes, but should that go as far as messing with the most important tournament? Probably not."