The Scottish Government has accused its opponents of scaremongering after reports claimed Scotland would have to apply to join the European Union if it left the UK.
Holyrood ministers now plan to contact the European Commission to raise their "serious concerns" about the matter.
The action comes after the commission was said to have written to the Lords Economic Affairs Committee which is investigating the impact of Scottish independence.
The Scotsman newspaper reported that the commission told the committee the UK's EU membership would "cease to apply" to an independent Scotland. According to the newspaper, the commission stated independence "would not have a neutral impact".
The letter is further reported to have said: "If a territory of a member state ceases to be part of that member state because it has become an independent state, then the treaties would cease to apply to that territory."
But while the committee has written to commission president Jose Manuel Barroso, asking about the possible impact of independence, he has yet to reply to them.
A spokesman for Mr Barroso said: "President Barroso has been invited to contribute to the House of Lords inquiry on the economic implications for the United Kingdom of Scottish independence. The president has not yet replied.
"The commission position is well known and set out in the series of responses given to European parliamentary questions. The commission has been very clear that we do not comment on specific situations but can only give a view in general."
In the wake of that, a spokesman for Deputy First Minister Nicola Sturgeon said the story is "falling apart at the seams, as are the scaremongering tactics of the anti-independence parties". The Scottish Government would also be writing to the commission, he said.
"The European Commission have now confirmed that no such letter has been sent. Serious questions now need to be asked as to where these claims came from and what role members of the House of Lords Committee and the UK political parties played in this fabricated story."