An independent Scotland could not afford to pay its welfare bill without cutting services or raising taxes, the UK Work and Pensions Secretary has said.
Speaking before an address in Glasgow, Conservative minister Iain Duncan Smith said a break-up of the Union would leave Scotland unable to meet the cost of getting people into employment or adequately supporting those who cannot work.
Mr Duncan Smith is to deliver a speech on the UK Government's controversial welfare reform plans. He will discuss the impact of the proposed universal credit system and is expected to touch on the independence debate.
Welfare spending is 6% higher north of the border, he said, and warned that North Sea oil and gas revenues would not meet the costs.
"Due to the reliance on the old heavy industries in many parts of the country, it makes perfect sense that we need to spend more money per head of population on welfare support in Scotland. I have no problem with that," he said.
"Thankfully, due to the United Kingdom and the commitment of the Westminster Government, we are able to ensure that money brought in, whether it be from the City of London or from North Sea oil, can be pooled and directed to wherever it is needed most.
"If the unthinkable were to happen, a Scottish Government would face a very stark choice of raising taxes or cutting services. This is not scaremongering, it's reality."
Mr Duncan Smith will address the Welfare to Work Scotland conference organised by the Centre for Economic and Social Inclusion.
He said universal credit would make a "radical" difference to getting people back into the workplace in Scotland and the rest of the UK. Under the scheme there will be a single monthly benefit payment, rather than weekly or fortnightly as at present, for people looking for work or on a low income.
Launched next year, it will replace income-based jobseeker's allowance, housing payments and other benefits.