Lorna Slater has ruled out further delays to the crisis-hit deposit return scheme (DRS) – warning such a move would wreck her “credibility” and add further misery to businesses.

The Scottish Government’s Circular Economy Minister said it would be “absolutely a kick in the teeth to industry” to delay the controversial initiative further, which is due to start in August.

The Greens MSP was speaking after SNP leadership candidate Kate Forbes, the Finance Secretary, said the DRS will cause “economic carnage” for businesses and backed calls to pause it.

Read more: Kate Forbes: SNP must stop anti-business attitude amid DRS 'carnage'

The scheme, set to begin in August, involves shoppers paying an extra 20p when purchasing drinks in a can or bottle, with the deposit returned when they bring back the empty container for recycling.

Producers have until midnight on Tuesday to sign up for the scheme.

SNP leadership candidate Ash Regan has said she would delay the DRS, saying it needs to be “returned and recycled so that it works for everyone”.

Ms Slater said at the weekend that small drinks producers may be given a one-year exemption from the planned scheme, but stressed on Tuesday that its introduction should not be delayed.

She told BBC Radio Scotland’s Good Morning Scotland programme: “No-one with any credibility to support business in Scotland would delay the scheme any further because those businesses that have made that substantial investment, those shops that have got their planning permission for their reverse vending machines, they don’t get their return on that investment until those 20 pences start flowing.

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“No-one with any credibility would delay that. The question on the table and the sensible question is what small producers can do to become compliant with the scheme, we’ve been working very closely with small producers, we’ve got an extra £22 million of cash on the table, cash flow support for them last week, we’ve got support for labelling, we’re working through the issues.

“One of the requests on the table from small producers is that grace period and that’s exactly what we’re working on to see how that would work with the scheme, bring those producers into the scheme at the time that works for them.”

SNP leadership candidate Humza Yousaf, Scotland’s Health Secretary, has said he would keep smaller businesses exempt from the scheme for at least the first year of operation if he becomes First Minister.

Asked what she thinks of the comment Ms Forbes made about “economic carnage”, Ms Slater said: “It would be absolutely a kick in the teeth to industry to delay this scheme.

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“Industry have put so much work into this, people have been recruited into posts, there is recruitment ongoing, we’ve got the sites for the sorting facilities, the trucks to collect all these materials, all of that is happening, that investment has been made and those business who have done the right thing, who are working towards this, they deserve that return on investment.

“I don’t believe anyone can credibly say they are supporting industry who would delay that, the question on the table is, and it is absolutely the right question, how we support small producers to participate in the scheme and that is an ongoing piece of work.”

Scottish Secretary Alister Jack has hinted the UK Government might not agree to a UK Internal Market Act exemption for the scheme; however, the UK Government said that following any decision it would be up to the Scottish Government whether they proceed with the scheme or not.

Read more: UK Government set to block Scotland's troubled Deposit Return Scheme

Ms Slater said that the Scottish Government has been following the agreed process to seek that exemption for the deposit return regulations from the internal market act.

She added: “We’re continuing to press the UK Government for a decision as soon as possible because, of course, businesses need that clarity from the UK Government.”

But Scottish Conservative MSP Maurice Golden has accused Ms Slater of "living in a parallel universe".

He said: "It beggars belief that she makes the extraordinary claim that any further delays to this scheme would be a kick in the teeth for industry, when that is exactly what they are crying out for her to announce.

“A sensible recycling system is much needed but the Deposit Return Scheme is completely unworkable in its current form.

“It is astonishing that Lorna Slater still could not answer basic questions this morning over what would happen to businesses if they didn’t sign up by tonight’s looming deadline."

Mr Golden added: “The minister responsible for delivering this scheme has become increasingly detached from reality.

"She has now effectively said thousands of concerned businesses have no credibility, because they are pleading – entirely correctly – for a delay while the problems with the scheme are resolved.

“Rather than ploughing ahead regardless, Lorna Slater should finally see sense and urgently pause this scheme.”