The Premiership is to expand to 14 clubs from the 2022-23 season, with no relegation from the top tier until the following campaign.

Next season's second-tier winners are also set to go up, with no prospect of Premiership relegation until 2023-24.

That will come in the form of a play-off before an annual one up, one down system returns for the 2024-25 season.

The move is one of several structural changes voted through by the Rugby Football Union council as part of their 'Covid Recovery Plan'.

"This is not ringfencing the Premiership as some have suggested," said RFU president Jeff Blackett.

"In three of the four seasons covered by this, and our previous decision, a Championship club will have the opportunity to be promoted.

"[The RFU] Council has control of what happens thereafter and is committed to maintaining the integrity of the league structure by ensuring that access to the Premiership will be retained in the future."

The council added that the changes will "improve the financial stability and sustainability of professional rugby", with clubs in the Premiership and Championship - as well as the Rugby Players' Association - all included in the "extensive consultation".

Also announced is an "intention" for Premiership clubs to have 15 English qualified players in each match day squad from August 2024 "to provide better England player development opportunities", while the current level of funding will remain for the Championship until 2024, with no relegation next season.

England men's players will be given extra time to prepare for the 2023 World Cup as part of the proposals.

Premiership clubs obtained £88m in loans through the government's Winter Sports Survival package last year, which was designed to help clubs overcome the financial impact of the coronavirus pandemic.

The decision has been welcomed by Premiership Rugby, with Nigel Melville, chairman of the Premiership Rugby Investor Board, saying the ambition was to make the league "the most exciting club rugby competition in the world".

"As well as giving support to a world-leading England team, the plan will create a stable platform for the professional game so that clubs can reset and rebuild after the unprecedented financial pressures of Covid," he said.

"With an agreed structure and expansion plan in place for the next three seasons, we can now focus on creating a more sustainable future, developing our talented home-grown players and bringing an attractive, competitive league to fans."