WESTMINSTER would stop representing Scotland's national interests overseas the instant there was a Yes vote for independence, the Foreign and Commonwealth Office (FCO) has warned.

Under the SNP's proposed timetable, Scotland would remain part of the UK for 18 months in the event of a Yes vote on September 18, only becoming legally independent on March 24, 2016.

During this transition period, Scotland would not yet have its own seat on international bodies such as the European Union, where in theory the UK would continue to speak for Scottish interests.

However, David Lidington, the Conservative Minister for Europe at the FCO, said Scotland would immediately be out in the cold.

Asked in a media briefing about Scotland's membership of the EU in the event of independence, he said it would not be in the UK's interest to have Scotland outside the EU, and so the UK would not veto its membership - although others might.

But that did not mean the UK would carry on helping Scotland as before, he stressed.

"The key point is this: now, and right up until referendum day, every United Kingdom minister - whatever responsibility they hold - is thinking about and representing the people of Scotland as much as any other part of the UK.

"If Scotland votes for independence, from that time on ministers in the UK Government will have a responsibility for people of the rest of the United Kingdom.

"It would be for ministers in Holyrood in those circumstances to make the case for Scotland.

"In those circumstances, ministers in the UK Government would be working all the time and thinking all the time about the people who elect us in England, Wales and Northern Ireland.

"If the people in Scotland chose a different way that's fine, but that changes our outlook."

There was no suggestion Scots would be denied UK embassy support or UK passports before 2016.

But the suggestion that Scotland's interests would be ignored by the UK prompted a furious response from the SNP.

Angus Robertson, SNP leader at Westminster, called the comments "an ill-thought out threat".

He said: "David Lidington has been caught not thinking through what he is saying about the period following a Yes vote.

"I fully expect the Whitehall spin machine to have to back-pedal yet again.

"This is the latest in a line of badly considered bluster aimed at scaring the people of Scotland in the lead-up to the referendum."