Jeremy Corbyn has warned Scots that independence would leave a glaring hole in the economy
Labour's firebrand leader warned separation would leave a "glaring hole" in the country's public finances.
It came as the Left-wing politician rejected Nicola Sturgeon's plan to keep Scotland in the European single market insisting leaving the trading zone must be "a UK-wide decision".
But Mr Corbyn failed to clarify if he would impose a three-line whip on Labour rebel MPs wanting to block Article 50, which will trigger Brexit talks.
He said his Commons bloc would be "asked" to back the start of the EU divorce process – though did not spell out if they would be punished for defying him.
Mr Corbyn put on a united front with Scottish Labour leader Kezia Dugdale following apparent policy rifts on the constitution and a power struggle over extra autonomy for the party north of the Border.
He used his first speech in Scotland of 2017 to launch a scathing attack on the SNP's draft Holyrood Budget and threats of a rerun of the divisive 2014 independence poll.
First Minister Ms Sturgeon has claimed another referendum is "looming" after Prime Minister Theresa May signalled she will reject SNP demands for a bespoke deal for Scotland.
It would lead to turbo-charged austerity
Labour leader Jeremy Corbyn
But speaking at a party event in Glasgow Mr Corbyn said: "It would lead to turbo-charged austerity and a glaring hole in the money required to fund essential services, and would not be in the interests of the people of Scotland."
He argued the case for breaking up Britain had "weakened" since 2014 because of plummeting North Sea oil revenues.
Mr Corbyn also insisted it would "not tackle the underlying problems facing Scotland" and mean, "political power would lie with the Edinburgh establishment" instead of London.
The Labour leader said separation would lead to 'turbo-charged austerity'
Sturgeon's top moments
Fri, December 9, 2016
Scotland's First Minister Nicola Sturgeon in pictures.
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Nicola Sturgeon visits Glaxo Smith Kline.
Attacking Ms Sturgeon's SNP administration he claimed "it was not standing up for Scotland" and had more in common with the Conservatives than his own party.
He also insisted June's Brexit vote could bring "opportunities" for Scotland, with further powers devolved to Holyrood.
His remarks drew a swift response from Mr Sturgeon on Twitter who branded his claims "rubbish".
She added: "If Corbyn wasn't leading such a pitifully ineffective opposition, the Tories wouldn't be getting away with half of what they are."
But Mr Corbyn later said she had failed to explain how an independent Scotland would deal with a £15 billion deficit.
He also rejected Nicola Sturgeon's plan to keep Scotland in the single market
"She needs to answer the question of the levels of austerity that would be necessary with the fall in tax income and the continuing austerity imposed of Scottish local government," he said.
Dealing with SNP demands for a different Brexit arrangement, Mr Corbyn said: "The question of single market access is and has to be a UK decision."
At least five of Mr Corbyn's MP's – including Edinburgh South politician Ian Murray – and four Shadow Cabinet members are rumoured to be considering a revolt over Article 50.
Asked to "clarify" if they would face a three-line whip he replied: "We will not block Article 50 because we have to respect the result of the referendum.
"But we will also use the opportunity of the initial Bill to implement Article 50 and the Great Repeal act to put forward a case for access to the single market, for social justice across Britain and for greater democracy across our whole society.
"Labour MPs are being asked to respect the result of the referendum, however difficult they might find that in different places and different circumstances."