Scottish independence is a “folly on a grand scale” that would significantly weaken global influence, Sir John Major told MPs.
The Conservative former prime minister said the UK would understandably be seen overseas as “damaged and diminished”.
Britain’s place on the United Nations Security Council would be “open to doubt” and its voice on other international bodies weakened if there was a Yes vote in next year’s referendum, he suggested.
He issued a stark warning to the SNP that it faced a decade-long fight to be admitted to the European Union as a separate member state.
And he renewed his warnings over the impact of any referendum on the UK’s membership of the EU – saying quitting Brussels would also represent a huge blow to influence.
Appearing before a House of Lords committee, the 70-year-old launched a strong attack on the idea of Scottish independence. Sir John said he found that, while on his global travels, the issue was increasingly a concern.
“It has come up in the Far East, it has come up in a number of countries. Simply because they would perceive a country that was damaged and diminished if a chunk of it voluntarily chose to leave,” he said.
“They are baffled as to why they should do so, but they do observe that if that happened it would diminish us in their eyes.”