Rugby Football Union (RFU) chief executive Bill Sweeney has confirmed the Welsh Rugby Union (WRU) has officially asked to join an Anglo-Welsh league.
The Prem hopes to expand from 10 to 12 teams for the 2029-30 season, with a "long-term ambition" to grow further.
Wales have four professional sides, Ospreys, Cardiff, Scarlets and Dragons, that currently play in the 16-team United Rugby Championship (URC), although the WRU has plans to cut one of those four teams.
Welsh rugby's governing body, along with the other national unions which includes teams from Scotland, Ireland, Italy and South Africa, are stakeholders in that league.
Now the RFU says the WRU has asked to be part of an Anglo-Welsh tournament.
"We have received a formal approach," Sweeney told BBC Radio Four.
"We asked for that and we wanted it in writing. We wanted to understand a few points and that has been submitted to us."
Three sides, Worcester, Wasps and London Irish, were forced to fold during the 2022-23 season when the Premiership - as it was then known - was reduced to 10 teams.
Traditional promotion and relegation to and from the top tier was scrapped from the start of the 2026-27 season after landmark changes to English rugby were voted through.
Instead of earning a play-off shot at replacing the Prem's bottom side by finishing top of the second-tier Champ and meeting the top flight's minimum standards, clubs will instead apply to join and be judged across a range of criteria.
Bids will be assessed on standard of play, finances, investment potential, infrastructure and how their geographical base could help spread the Prem's appeal, among other factors.
Conditions were initially set that any team wanting to play in the Prem will need to complete a campaign in the Champ before being considered.
Sweeney has reaffirmed his commitment to expanding the English game, with no formal talks having yet taken place with their Welsh counterparts.
"Our primary focus is on the expansion of the English game," said Sweeney.
"We have had some developments there recently with no longer having an automatic promotion or relegation but having an expansion game.
"Financial criteria, fan base, geographical location, ability on the field of play, will determine whether you can get into the Prem or not.
"We see that as a way of expanding the 10 teams and our focus is on expanding the English game.
"But we have been approached [by the WRU] and it is responsible for us to go back and ask more questions."
Those questions will be answers about what is happening in the chaotic state of the Welsh domestic game.
The WRU is currently in the middle of cutting the number of Welsh professional teams from four to three by 2028.
The governing body has announced it will award licences to Cardiff and Dragons, pitting Ospreys and Scarlets against each other for the west Wales licence with a final decision expected by the summer of 2027.
New WRU chair Lyndon Faulkner came in and suggested he will look at everything, including keeping four professional sides, while he indicated he was a fan of an Anglo-Welsh tournament.
Now the WRU is trying to get a possible two sides into an Anglo-Welsh tournament, which was the number of professional teams the Union initially wanted to maintain when its reduction policy started.
The URC has been contacted by the BBC to see whether the WRU would face any legal action over lobbying to join another league, as it has committed to providing four sides to the current URC competition for another two years.
"There are some fundamental questions there," said Sweeney.
"We don't yet have a clear understanding of how they would legally exit the URC which they are a member of, so that has to be clarified in some detail.
"Going into cross-border competition has different ramifications and we have to be clear around the complexities."
When approached after Sweeney's comments, the WRU referred to a statement made last week: "Welsh men's professional teams compete in the URC and the WRU is committed to providing four teams to the URC until the end of the 2027-28 season.
"By the end of this season, the WRU will have determined the future operating model for the men's game in Wales.
"The WRU will continue to work with other shareholders in the URC on future Welsh representation in the competition.
"The WRU keeps under review the competition opportunities which may be available across the game and could be in the best interests of Welsh rugby.
"The idea of Anglo-Welsh competitions is something often debated by Welsh rugby fans.
"The WRU understands the appeal of the English top flight, which is why we are pitching for two of our women's teams, Brython Thunder and Gwalia Lightning, to be included in Premiership Women's Rugby."
