The UK government's Welsh secretary has called on the Welsh Government to hold a referendum on its plans to expand the size of the Senedd.
Simon Hart said it should “seek the approval of its voters” and hold a referendum before increasing the number of Senedd Members.
In joint plans as part of their co-operation agreement, the Labour-led government and Plaid Cymru has proposed expanding the size of the Welsh parliament from its current 60 members to 96.
As part of the reform, Welsh election could also see a more proportional voting system adopted and gender quotas for candidates.
However, in answer to a question from English MP Danny Kruger at Wales Office questions in Westminster, Mr Hart said: “I have to say if this Government was making suggestions of this nature involving the constitution and voting measures, I have every belief that pretty well all of the members opposite would be saying this should be subject to a public referendum at the very least.
“So, I would suggest that the proper course of action for Welsh Government is to seek the approval of its voters before proceeding with any of these costly measures."
Reform of the Senedd was included in both Plaid Cymru and Wlesh Labour's manifestos for the 2021 Senedd elections.
Combined, the two parties, who signed their co-operation agreement in December, won 43 of the Senedd's 60 seats in May 2021, giving them what is known as the 'supermajority' required to get the plan through the Welsh Parliament.
Neither party included a commitment to a referendum on the plans in their manifestos.
The Conservatives in the Senedd have also opposed the plans as 'wasteful', but its supporters say more MSs are needed to improve scrutiny and hold the Welsh Government to account.
In February, a poll suggested a majority of people in Wales would support an increase in the number of politicians in the Senedd.
In response to Mr Hart's calls, a number of people on social media pointed to the fact there was no referendum on plans to cut the number of MPs in Wales from 40 to 32.