Scotland risks entering its post-independence negotiations from a "position of weakness" and could emerge with relatively little influence on the world stage, the Scottish Secretary will tell a US audience.
Michael Moore will tell an audience at Washington DC's Georgetown University that an independent Scotland would have "reduced clout" and "diluted influence" in European and world affairs, in contrast to the diminished but still "comparatively large, wealthy and powerful" United Kingdom.
In advance extracts from the speech, Mr Moore said Scots who vote 'Yes' to independence risk "shedding influence over their own destiny".
The Scottish Government accepts that Scotland will have to negotiate its European Union (EU) terms of membership but argues that this will be done from within as a continuing member state. But Mr Moore said that while the remainder of the UK is "likely" to continue in the EU, Scotland "would be required to seek membership".
Mr Moore will urge the pro-independence camp to explain how Scotland will then avoid joining the euro and setting up border controls with England. Independence risks damaging the UK's "triple-lock guarantee" of an integrated domestic market, an expanding European market and a liberalising global market, he said.
Mr Moore's speech comes after a Washington Post editorial warned Scotland would be "unable to contribute meaningfully to global security". The editorial prompted a strong rebuttal from the SNP, culminating in an article by First Minister Alex Salmond in the Post on Saturday challenging its factual errors and "disappointing" tone.
Mr Moore said: "Based on legal and academic opinion, the most likely outcome in the event of Scotland leaving the UK, is that the remaining UK would continue as an EU member state. By definition, the remaining UK would be a smaller entity, shedding influence, but it would remain a comparatively large, wealthy and powerful player.
"Scotland, as a new state, would be required to seek membership, on negotiated terms, with the unanimous approval of every other EU member state. That means a smaller state, negotiating for influence, from a position of weakness."
A spokesman for Deputy First Minister Nicola Sturgeon, who is leading the Scottish Government's independence drive, said: "Mr Moore appears to be implying that it is bad for Scotland to decide our own policy and that it doesn't already happen.
"Yet the fact is that with the independence we already have we have more successful inward investment, small business support and exports promotion policy than Westminster, as well as in health, police numbers and student support. We would have equally successful policies with the full powers of independence in the reserved areas, where the one thing holding us back is Westminster austerity."