The deputy leader of the SNP has denied that Humza Yousaf has given the UK Government an ultimatum to change its tune on the troubled deposit return scheme (DRS).

After the UK Government blocked the DRS from being rolled out in full by insisting that glass is removed from the scheme, Mr Yousaf called for a rethink by Westminster.

Mr Yousaf has set today as the deadline for the removal of UK Government conditions on the DRS, warning the scheme could potentially be scrapped if ministers do not back down.

The FM set the timeline in a letter to Prime Minister Rishi Sunak on Saturday, saying a failure to revoke the conditions would put the scheme in “grave danger”.

Read more: Yousaf accuses Jack of 'making intentionally misleading' DRS claims

Last week, UK ministers approved a partial exemption to the Internal Market Act for the deposit scheme, but stipulated glass cannot be involved north of the border.

The deadline was set to allow for the Scottish Cabinet to discuss a response on Tuesday during its regular weekly meeting and provide an update to Holyrood.

However, the chance of the conditions being revoked seemed unlikely on Sunday, when Scottish Secretary Alister Jack said the Prime Minister should not back down.

Speaking BBC Good Morning Scotland, deputy SNP leader, Keith Brown, suggested that the ask of Mr Yousaf was not an ultimatum.

Read more: Humza Yousaf urges Rishi Sunak to rethink DRS intervention

Asked if it was an ultimatum, Mr Brown said: “No, but I think Humza Yousaf's terms of his letter are perfectly clear, and you know them as well as I do.

“What they're saying is, he finds it very hard to see how you can go ahead if it's to be sabotaged by taking out what was previously agreed.

"What's the position of the Welsh Government, what was decided by the Scottish Parliament back in 2020, which has been consulted upon to include glass?

“If all these things are to be set aside by the UK Government, then of course, it leaves a very different scheme, and the Scottish Government will have taken decision on that tomorrow.”

Mr Brown also pointed to “a £20,000 donation, which remains unanswered from the industry a few weeks after the Conservatives had agreed to change their mind on DRS”.

He added: “So this is what's underlying this current crisis and I would hope that Rishi Sunak can bring some pressure to bear on Alister Jack to see some sense.”

The former justice secretary added that Mr Jack has carried out “a misrepresentation” by “trying to upset the understanding of the public” about what recycled glass would be used for under the scheme.

Read more: Lorna Slater hints DRS could be axed due to UK Government 'sabotage'

Speaking of Mr Jack, Mr Brown said: “He said yesterday in a scandalous statement, that the glass will be used to basically provide road fill for road surfaces when Circulatory Scotland said that's absolutely not the case.”

Mr Brown was asked about statements made by SNP ministers, including the First Minister, that have been branded misleading over claims 600 million bottles won’t be removed from streets, beaches and parks if the DRS does not go ahead.

Mr Brown refused to say if the statement is true, insisting that “the government will have its own calculations”.

He added: “The underlying problem and everybody knows this, is the problem with bottles which are lying in parks, which litter our countryside, which litter our urban areas, and this is a serious effort to deal with them.”

But Scottish Conservative MSP Maurice Golden, accused Mr Brown of “yet another example of desperate spin and deflection from the SNP-Greens over Lorna Slater’s shambolic Deposit Return Scheme”.

He added: “Keith Brown was utterly disingenuous in claiming that C&C’s letter to the Secretary of State – stating that their position had been misrepresented in media leaks – was somehow not a criticism of the Scottish Government because it didn’t actually name them.

“Given the letter was addressed to Humza Yousaf and a highly selective part of it then appeared in the media, who else could C&C have been referring to?

“Keith Brown also seemed to endorse Humza Yousaf’s scaremongering nonsense that if glass is excluded from the scheme, Scotland’s streets will be littered with 600 million bottles.

“The SNP-Greens are resorting to absurd ultimatums, dodgy stats and deflection to try to disguise the reality – that they have made a dog’s dinner of DRS from day one, by refusing to heed the warnings of businesses and recklessly ploughing ahead with an unworkable scheme.”