Carl Bildt was recently quoted saying that independence will lead to the "Balkanisation" of the British Isles, with serious knock-on consequences for the European Union.
A "Yes" vote on September 18 would spark a painful process raising questions about relationships with Ireland and the UK's role in European politics, Carl Bildt told the Financial Times newspaper last week.
Predicting unforeseen chain reactions if Scots first vote to leave the rest of the UK, he told the FT: "The Balkanisation of the British Isles is something we are not looking forward to.
"It opens up a lot, primarily in Scotland but also in the UK. What are the implications for the Irish question? What happens in Ulster?"
As well as raising his concern about the Scottish referendum, he warned that taking the UK out of the EU would be a "disaster". Prime Minister David Cameron proposes holding a referendum on the UK's membership by 2017.
Mr Salmond said the use of the word "Balkanisation" was insulting to the democratic process in Scotland.
The Scottish First Minister told the BBC: "I think the term Balkanisation was very foolish.
"Insulting to this democratic process in Scotland but also insulting to the new European member states from the Balkans who are now part of the democracy of the European Union."
Scottish Liberal Democrat leader Willie Rennie said Mr Salmond should listen to the "growing chorus of leaders across the world" who have expressed concern about the implications of a Yes vote.
Mr Rennie said: "Whilst I would not use the word 'Balkanisation' the message from Carl Bildt and many others on the global stage is clear - Scotland and the UK would be diminished in the world if we separate. We are stronger together.
"What is foolish is for Alex Salmond to continue his world tour lecturing the world's leaders that they are wrong and only he is right."
Last week US president Barack Obama said America's interest in the Scottish referendum issue was to ensure it retained a "strong, robust, united and effective ally".