London – World Rugby’s controversial plan for a Nations Championship suffered a setback when England’s Rugby Football Union said on Tuesday the new format carried a potentially “catastrophic” risk which they were not prepared to accept.

World rugby chiefs want to launch a new cross-hemisphere contest in 2022, in which the winners of the Six Nations would face off against the top team from an expanded, six-team Rugby Championship in an end-of-year final. The proposed format could also include relegation from the Six Nations, probably, given the competition structure, for two years.

The plans include three divisions and promotion and relegation. The competition would be backed by a record commercial partnership with nearly £5 billion ($6.6 billion) of investment.

But some European unions are reportedly unconvinced by the proposals.

The English RFU’s acting chief executive Nigel Melville warned of the cost of relegation from the lucrative Six Nations – the annual northern hemisphere competition.

In a comment that appeared to refer to reports that dropping to a second-tier competition, might force the sale of the national stadium, Twickenham, he said the RFU would not allow ownership of its 82,000-capacity ground to be endangered.

“I think we make sure it doesn’t arise,” he said. “That solves that problem. You just don’t want to get into a situation where you’re making decisions like that.

“For us it could be catastrophic being relegated, commercially. To be relegated, the catastrophe isn’t just the team being relegated, it’s our ability to fund the game as a governing body in England.

“Can we fund the community game in England to the level we do now if we don’t have the revenues we have?

“And on the point of promotion and relegation, there’s no promotion and relegation in a Lions year and there’s no tournament in a World Cup year.

“So when you’re relegated, you’re relegated for two years, not one. It’s not quite up and down, one season on the naughty step and go back up, it’s actually two years and that could be a disaster for people.”