A House of Commons select committee has called on David Cameron's Government to scrap the "bedroom tax" changes to housing benefit.
The Scottish Affairs Committee said that while ministers considered whether to repeal the measure, the Government should suspend the penalty for claimants who cannot reasonably be offered alternative accommodation.
The MPs said the measure, which cuts housing benefit for social tenants deemed to have a spare room, was " a budget cut suffered by those in greatest need".
The interim report was opposed by Tory and Liberal Democrat MPs on the Labour-led committee, but they failed to prevent it being produced.
The Government reduced entitlement to housing benefit for working-age tenants in April 2013. Those with an extra bedroom have a reduction of 14% to their eligible rent, and those with two or more extra bedrooms lose 25%.
The Government estimated that 80,000 claimants in Scotland would be affected by the bedroom tax, with an average weekly loss of £12.
The committee's Labour chairman Ian Davidson said: " This is an interim report because, while the impact of the bedroom tax cannot yet be fully quantified, it is already clear that it is a cruel burden being placed upon the shoulders of those least able to bear it.
"We have produced an interim report because some glaring flaws are already apparent and notwithstanding our call for the tax to be abolished, we wish to draw these faults to the Government's attention while it is conducting a review.
"We intend to explore more fully not only design flaws but also what can and should be done by the Scottish Government, social landlords and others to mitigate its effects on the vulnerable in Scotland."
A Department for Work and Pensions spokesman said: " Our reforms ensure that families receive housing benefit for the number of bedrooms they need - but that taxpayers do not cover the costs of claimants' spare rooms.
"We have protected the most vulnerable by ensuring a disabled child can have their own room and bedrooms are allowed for live-in carers - as well as providing Scottish councils with over £10 million to help tenants through our reforms."
Angus Robertson MP, SNP leader at Westminster, said: "The bedroom tax is a deeply unfair policy which will be scrapped in an independent Scotland.
"It is a shame that Labour MPs did not feel so strongly on November 12 this year - at their own debate in the House of Commons when there was a real opportunity to abolish this punitive tax - that 47 Labour members didn't even bother to turn up including - shamefully - 10 Scottish Labour MPs .
"Had they bothered, the bedroom tax would have been consigned to history. It is even more shocking that one of the 10 Labour MPs who could not be bothered to get rid of the bedroom tax when they had an opportunity was a member of this committee."
A Scottish Government spokesman said: "The 'bedroom tax' is causing misery for thousands of Scots who are paying a heavy price for Westminster decisions.
"The Scottish Government are already doing all we can with the powers we currently have to mitigate the worst impact of those decisions, including the provision of £40 million in discretionary housing payments to help those people who are struggling the most.
"The Scottish Welfare Fund has given extra funding to advice agencies at the front line and provides vital help for those hit by the bedroom tax.
"Only an independent Scottish Parliament will give us the powers we need to scrap the bedroom tax."