Scotland’s deposit return charge of 20 pence per bottle could be changed by the UK Government amid fears Tory ministers could choose to “impose” their proposals on devolved nations.

Greens Circular Economy Minister Lorna Slater has announced a fourth delay to the deposit return scheme (DRS) until October 2025 to “align” with the UK Government’s own policy.

The Scottish Government has pushed back the launch date after claiming the exclusion of glass under the UK Government’s conditions to agree to an exemption of the Internal Market Act.

Speaking to Holyrood’s Net Zero Committee, Ms Slater said the intervention by Tory ministers was “deeply regrettable”, claiming it was made “at the 11th hour”, despite also admitting talks had been going on for years between the two governments.

Read more: SNP raised DRS concerns three years ago despite '11th hour' claim

She added that the Scottish Government has been given “no detail on what we are expected to align to”.

Turning to the next steps, Ms Slater said she will undertake talks with the other UK nations with a “spirit of collaboration”.

She said: “The process is more convoluted than any of us would wish.”

The minister will raise the issues with UK minister Rebecca Powell at a meeting on Wednesday.

Ms Slater told MSPs that the Scottish Government has drawn up “a coherent scheme that is on the books that is workable with business”.

Read more: Analysis: Calling the UK Government's bluff on glass has spectacularly failed

But she warned that the UK Government could be set on “inventing something entirely different that they will impose on us”.

Ms Slater claimed that the common framework in which the two governments discuss matters has “effectively been smashed up” by the DRS intervention.

Euan Page, the Scottish Government’s head of UK frameworks, constitution and UK relations division, said that the “DRS episode” has placed “enormous strain” on the frameworks.

Ms Slater added: “It is not clear to me how we move forward if that common framework process can be disregarded.”

The minister warned that the lack of clarity from the UK Government throws up the prospect that Westminster could “develop something entirely independently and impose it on the devolved nations”.

The minister was asked whether the Scottish Government’s 20 pence per container charge should be imposed on the rest of the UK to keep a level playing field in the internal market.

Read more: Humza Yousaf confirms 'no case' to give businesses DRS compensation

In response, Ms Slater said: “The Scottish Parliament should be able to legislate on fully devolved matters.”

Committee convener Edward Mountain raised concerns the Scottish Government is “wedded to a figure” of 20 pence per container.

David McPhee, the Scottish Government’s deputy director of the DRS, told MSPs that the UK Government has “not made a decision yet on what an appropriate level would be” as a deposit charge on containers.”

Ms Slater added that “it absolutely has not been discussed on a four-nations basis”.

Asked if she took “legal advice” specifically on pushing the launch date back to October 2025, Ms Slater said it was “a matter on which I am not able to discuss”.