The UK's emergency pension fund provider believes independence would bring a higher risk of work pensions going bust, according to pro-Union campaigners.

Better Together said it had accessed papers revealing the concerns of the Pensions Protection Fund (PPF) about "more schemes going bust" in an independent Scotland since an EU directive means that UK-wide schemes would be deemed ''cross-border'' and need to be fully funded.

The issue was previously raised by the Institute of Chartered Accountants of Scotland, which said changes to pension rules in the event of a yes vote could force substantial costs on employers with unfunded schemes.

The papers released under the Freedom of Information Act said Scottish Government officials' knowledge of pensions was "very low" when they contacted the PPF with a query, according to Better Together.

The function of the PPF is to provide compensation to members of pension schemes where there are insufficient assets to pay out. To help fund the plan, compulsory annual levies are charged on all eligible schemes.

Shadow pensions minister Gregg McClymont MP said: "These revelations are a further blow to the SNP's pensions plans.

"Coming so soon after pension fund managers highlighted the risk to pensions from independence, the people who step in when things go wrong have now said that pensions schemes could close if we separate from the UK.

"The Pensions Protection Fund is a good example of how pooling and sharing our resources across the whole of the UK is good for Scotland's pensioners. Why would we want to put this at risk?

"The fact that the PPF describe the Scottish Government as having a 'low level' of pensions knowledge exposes just how ill-prepared they are."

A Scottish Government spokeswoman said: "There is nothing new in this which mostly pre-dates the Scottish Government's pensions paper which clearly set out protection for Scotland's pensioners.

"With independence, pensions will not only be paid on time and in full, but will benefit from a triple lock on the state pension, guaranteeing pensions rise in line with living costs, and the pension age will be reviewed by an independent commission to ensure it is appropriate for people in Scotland.

"With social protection spending - including pensions - in Scotland taking up a lower portion of our national GDP than across the UK as a whole pensions are more affordable than in the UK.

"Discussion with both the EU, UK and pensions industry would be of benefit and we remain disappointed that the UK Government refuses to take part in any such talks."