The UK Government is promising "improvements" will be made to a key piece of post-Brexit legislation - with trade policy minister Douglas Alexander conceding there are "real concerns" about how the laws have operated to date.
Mr Alexander however made clear that ministers have not considered scrapping the Internal Market Act (IMA), with the Scottish Government branding the results of the Westminster review "completely unacceptable".
Angus Robertson, the Scottish Government's Constitution Secretary, insisted the legislation - which Holyrood has twice voted against - "undermines" the Scottish Parliament.
Mr Alexander however said the UK Government has "been explicit about the need for businesses to have certainty", saying this is "why the review has not considered repeal of the Act or any of its provisions".
He said the UK Government has instead "pledged to explore improvements in the way the Act's provisions operate", adding "very real concerns" have been raised.
Following the UK's departure from the European Union, the then Tory UK government introduced the IMA in order to create a single market across the four nations of the UK.
The legislation however caused difficulties for the Scottish Government when it attempted to introduce a deposit return scheme for empty cans and bottles ahead of the rest of the UK.
In the wake of the review, the UK Government is promising changes, including the introduction of exclusions to the legislation, that have been agreed by all governments within a common framework.
As well as considering economic impacts, issues of environmental protection and public health will also be looked at for exclusions - with the UK Government saying this ensures a "balance of factors is considered".
Mr Alexander stressed the importance of having a "well-functioning UK internal market" as part of the Government's "ambition to improve economic growth for the benefit of businesses and people in all parts of our country".
He added: "Latest figures show that trade between the four nations of the UK is valued at £129 billion and that it is particularly important to the economies of Scotland, Wales, and Northern Ireland."
But Mr Robertson insisted the IMA had been introduced by the previous Conservative government "without the consent of any devolved government or Parliament".
Speaking about the legislation, he added: "It undermines the ability of the Scottish Parliament to use its powers to pursue devolved social and economic objectives in Scotland for the people to which it is accountable.
"It introduces radical new uncertainty as to the effect of laws passed by the Scottish Parliament and effectively provides a veto to UK ministers.
"Nothing set out in the UK Government's response to the review changes this position, which is completely unacceptable.
"The conclusion of the review falls well short of our stated position of repeal and replace the Internal Market Act, and indeed short of the legislative change required to mitigate the most damaging aspects of the operation of the IMA.
"It is important also to note that the Scottish Parliament has twice voted to repeal the Act - since it is fundamentally misconceived and incompatible with devolution."
While he said the Scottish Government welcomes the UK Government's intention "to address some of the most egregious issues with the function of the IMA exclusions process", he added that SNP ministers "remain concerned that there is no clear vehicle to give meaningful effect to these changes, which work against our shared interests to promote growth, protect jobs and ensure seamless trade across the UK nations".