The SNP are now pushing for a “far more extreme version of independence than we have ever seen”, according to Gordon Brown.
Speaking at a European election campaign rally in Glasgow on Monday, the former prime minister accused the party of moving away from its policy positions in 2014, such as on currency.
At the SNP conference last month, members voted to replace the pound with a separate Scottish currency “as soon as practicable” – although First Minister Nicola Sturgeon has indicated she would only want to do soon when six key tests are met.
“In 2014, Alex Salmond told us we were only leaving the political union, that was all, we were staying in all the other unions,” Mr Brown said.
“But what’s the policy now? It’s a far more extreme version of independence. They’ve moved from soft independence to hard independence.
“Because now they will leave the British pound, they’ll leave the UK currency union. That is their decision.
“First of all, they’re going to adopt the pound for a few years and then they’re going to leave it with a Scottish pound being set up.
“It’s nothing like the policy of 2014 when Alex Salmond said it would be part of the British pound, it would be part of the UK monetary policy committee.
“Immediately they get independence, if they ever got it, they would leave the UK currency.”
Mr Brown, who joined Scottish Labour leader Richard Leonard at the party’s European election candidates at the event, also said independence would mean separating Scotland from UK trade and social welfare policy.
He said: “They want to stay in the European Union and they want to leave Britain so they have to leave the UK customs union as well.
“They have to leave the UK single market, they’ll leave the UK social welfare union, because pensions and everything else will have to be decided in Scotland and not decided as part of the UK pensions scheme we’ve all contributed to.
“So this is a far more extreme policy that the SNP are now putting forward and people have got to recognise if you vote for the SNP on Thursday, you’re voting to give recognition and legitimacy and credibility to a more extreme form of independence than ever we’ve seen.
“Independence is separation. That means a separate currency, a separate customs union from the rest of the United Kingdom, a separate single market from the rest of the United Kingdom, a separate social welfare union.
“That is a more extreme version than we have ever seen and people should know this by Thursday.”
Mr Brown also accused the Scottish Conservatives of delaying the transfer of powers from Europe to Holyrood.
He said: “They’re allowing powers that have been transferred from Europe to Westminster not to come to the Scottish Parliament for years – a more extreme version of centralisation than ever before.”
Mr Brown concluded: “This is where we are – two parties that claim to be the governing and opposition parties in Scotland that cannot talk about their record because it is so bad, that cannot answer questions on their main policy to leave Europe or to leave the United Kingdom, and are now interested only in this Punch and Judy fight on the constitution that allows them to talk incessantly about referenda in Scotland, about constitutional minutiae, while neglecting all the issues that worry the Scottish people.”
Christian Allard, an SNP European election candidate. said: “People in Scotland remember Gordon Brown as playing a key role in the campaign to ensure that we would continue having to live under Tory governments we didn’t vote for – and now that Tory government is trying to drag Scotland out of the EU against our will.
“So if he wants people to even consider listening to Labour on anything, Mr Brown should start by apologising to Scotland for the mess he has helped create.
“Voters in Scotland can send a message to the parties who have ignored Scotland’s people and our Parliament by voting SNP on Thursday.
“While Labour are all over the place on Brexit, a vote for the SNP is a vote to stop Brexit.”