Growing uncertainty around Scotland’s recycling scheme and plans to ban alcohol advertising threaten to overshadow attempts by the SNP leadership contenders to focus on jobs and the economy.

The UK government has indicated that it would block the deposit return scheme amid calls for Holyrood to stall it until a UK-wide project is ready.

Lorna Slater, the Circularity minister leading the scheme, has admitted that an opt-out from the UK Internal Market Act is needed for the scheme to proceed.

Scottish ministers have not approached Westminster for an exemption, but the Scottish Secretary Alister Jack has called for a united approach.

The latest developments come as Kate Forbes will today set out her economic vision at the Cairngorm brewery in Aviemore amid her calls for the DRS to be reviewed following a series of concerns over its impact on the drinks and retail sectors who fear the costs involved will put them out of business.

In a television interview, fellow leadership contender Humza Yousaf described the DRS as “important” but said he would exclude small businesses for the first year of the scheme’s operation.

Ms Slater insists the scheme will go ahead in August but admitted yesterday that small businesses may be given a one-year “grace period” to ensure they are ready to implement it.

The muddle over its operation has thrown the future of the scheme into doubt. Furthermore, if Ms Forbes wins the leadership contest she may jettison Ms Slater’s Greens from government, putting her out of a job before the scheme’s scheduled start date in August.

Scottish Labour Net Zero spokesperson Colin Smyth accused the government of “making policy up on the hoof”.

He said: “Labour has been pressing for a phased in approach to any Deposit Return Scheme to protect small businesses, so any U-turn on this by the government would be welcome.”

Businesses are turning up pressure ahead of tomorrow’s deadline for drinks providers to register for the scheme or face being banned from selling their products in Scotland.

Dougal Sharp, founder of brewer and pubs chain Innis & Gunn, has been at the forefront of opposition to the register, accusing Circularity Scotland of “extortion”. He would not say whether his company would sign up, but said the risks were clear either way. “It is going down to the wire,” he said.

Plans to ban alcohol advertising are also turning into major battle with the country’s drinks and hospitality industries.

The Scottish Tourism Alliance (STA) has today published an open letter signed by 27 organisations calling for the new First Minister to halt the proposal. Ms Forbes has indicated that she would not pursue the ban.

Marc Crothall, CEO of the STA, says the policy is “ill-conceived, high risk and delivers self-inflicted damage to swathes of Scotland’s communities and the positioning of our country as a globally attractive visitor destination”.

The letter adds: “Restricting the ability to promote and market products responsibly will remove a vital route to market for producers, including new business start-ups, and go against the Scottish Government’s and the food and drinks industry shared aim to double the turnover of the sector by 2030.”

Mr Yousaf will today unveil plans to substantially increase Scotland’s green energy output and slash soaring energy bills. He will also promise to hike the budget for the Scottish National Investment Bank from £2 billion over the next decade to £10bn.

Ash Regan yesterday called for more focus on the north east oil and gas sector which she claims has been let down by every major political party. She said she would fight to secure a carbon capture project for the region.

As the leadership candidates attempt to focus on the economy, a survey commissioned by the pro-union Scotland Business UK campaign claims independence would slash economic output by at least 10% and cost the country 250,000 jobs. No timescale for this to take place was given.

Economist and report author Richard Marsh, who contributed to Nicola Sturgeon’s Sustainable Growth Commission, claims that significant reductions in public spending, even if partly offset by tax rises, would hit Scotland’s most deprived communities the hardest.

Robert Kilgour, the founder of SBUK, said the candidates to succeed Ms Sturgeon as First Minister “would do well to reflect on [the report’s] findings and explain to the people of Scotland how and why slashing a tenth of the economy and hundreds of thousands of jobs would serve the interests of businesses and communities”.

Ronald MacDonald, professor of macroeconomics at the Adam Smith Business School at Glasgow University, said Mr Marsh’s paper showed that an independent Scottish government “would have eye-watering implications for public sector spending, employment and economic output”.

However, Paul McLennan, the SNP MSP for East Lothian, described Mr Marsh’s report as “a preposterous scare story”.

He said that “no one with credibility still suggests Scotland is too wee and too poor to be a successful independent nation. Even hardline unionist politicians are too embarrassed to peddle this brazen scaremongering these days.”