Newport Gwent Dragons chief executive Gareth Davies has admitted Welsh regions may be forced to join the Aviva Premiership if they fail to reach agreement with the Welsh Rugby Union (WRU).
The Ospreys, Scarlets, Cardiff Blues and Dragons have long since been linked with a move from the RaboDirect Pro12 but former Wales fly-half Davies has now publicly confirmed them.
Regional Rugby Wales, the organisation representing the regions, is at odds with the WRU over competition structures and revenues from next season, as well as how to keep top Welsh talent within the country.
The regions are keen to join the Rugby Champions Cup, an alternative to the Heineken Cup proposed by the English clubs, which they claim will earn them an extra £1m in revenue per season.
In contrast, the WRU is committed to fielding sides from the principality in the existing European competition, currently run by European Rugby Cup (ERC), as well as the RaboDirect Pro12.
When asked if joining the English top-flight was an option, Davies said: "It is an option.
"Our understanding with the English clubs, it is quite solid, whilst not underestimating the enormous hurdles that are in the way of that happening.
"What are our options? The European Cup will be an extended Pro 12 in effect and I cannot see the tills ringing to see us play Zebre for the fourth time in a season.
"The Pro 12 does not have a sponsor and the Italians claimed this week they are pulling out. What options do we have?
"We need to look at this new European competition and commit ourselves to the domestic league."
An Anglo-Welsh tournament would require the support of the WRU, the Rugby Football Union and the International Rugby Board though, a scenario which appears unlikely.
The two parties failed to agree an extension to the Participation Agreement by the end of December, with the regions then proposing a new deadline of 31 January.
The WRU subsequently suggested it could form new sides to represent Wales in their chosen competitions but chief executive Roger Lewis has denied that was the case.
"I have not had any private conversations about setting up new regions. I am committed to making the four regions work," he said.
"Let's treat this with the seriousness it deserves. This is Welsh rugby and we will continue to work until we get the right solution for all of Welsh rugby.
"We are not going to play media games on deadlines. We did not set the December 31 deadline and we will not set one of January 31.
"I don't want to get stuck into a corner. The real question is, where will the regions walk to?
"The RFU have told us they will not let the Welsh regions join the Aviva Premiership. They have told us."