Coalition Government sources have warned of the "potentially terrifying" effects of independence on investments, life insurance policies and whether Scotland could withstand another banking crisis.
Insiders said the possible ramifications for financial services were "scary".
The UK Government is preparing to release a report into the sector as part of its ongoing investigation into the consequences of independence. It is expected to highlight that, following independence, most Scottish mortgages and life insurance plans would be held by companies based in a foreign country.
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The report is also understood to have considered how an independent Scotland might deal with a banking crisis like that of 2008.
The UK Government bailed out the Royal Bank of Scotland to the tune of £46 billion, later offering another £275bn in extra funding and guarantees.
Critics have questioned whether an independent Scotland would have been able to afford such sums.
Whitehall officials have also looked at whether independence would affect the flow of credit into the economy, a key driver of the 2008 crash, as well as the impact it could have on economic growth and jobs.
Insiders point out that financial services are highly integrated across the UK. Life insurance companies based in Scotland sell 6% of their policies inside Scotland and the rest to customers in other parts of the UK.
Similarly, most Scots life insurance policies, 78%, are with companies based outside Scotland. In addition, mortgage firms based in Scotland sell just 16% of their products here.