Ian Blackford has insisted the UK Government will continue to pay the pensions of older people living in Scotland in the wake of independence.
The SNP's leader at Westminster claimed Scots workers would have a right to receive a state pension after years of paying National Insurance contributions to the UK Treasury.
The MP pointed to the example of pensioners who choose to live abroad in another European country but can still claim their basic pension.
Opposition politicians claimed it was "blatantly inaccurate" to claim pensions would be unaffected if Scots voted for independence at a future referendum.
Steve Webb, the UK pensions minister in 2014, said people who had "accumulated rights" would be entitled to current levels of state pension in an independent Scotland.
But Danny Alexander, then chief secretary to the Treasury, repeatedly warned about the insecurity of pensions if Scotland voted to leave the UK.
Ian Blackford insisted in an interview yesterday the position was "clear" on who would meet entitlements.
He told ITV Border: "This was an issue that was discussed in 2014.
"But let's be clear about this, the Chief Secretary to the Treasury made it clear the UK retained an obligation to pay pensions to those who had paid National Insurance.
"That's a matter of precedence."
He continued: "The Scottish Government would take on the responsibility of its pensioners. Let's not forget we have the lowest state pension in Western Europe at the moment.
"Pensioners are being short-changed. It's Westminster that has removed the Triple Lock.
"The point is, it's an obligation on the UK Government to meet the commitment to pensioners who have paid National Insurance contributions.
"They have paid the right to receive that pension. You can argue about the mechanism over how that is transferred, and that will be debated, but it's right the UK Government meets its right to pensioners, regardless of where they are.
"If you or I, as UK citizens, go and live and in another European country then our right to that UK pension remains.
"Scottish pensioners have that right. They have paid National Insurance over a long period to get that. That will remain."
When it was pointed to him that National Insurance payments covers only existing pensions, Blackford responded: "You are paying National Insurance as an entitlement to a future pension.
"That's the whole point of the principle. You pay into a National Insurance fund, and the UK is responsible for the disbursement of that, but that's a right to a UK pension - no ifs, no buts, about that."
Responding to Blackford's interview, Labour MSP Paul Sweeney said: "National Insurance contributions are also a precondition for accessing Jobseekers' Allowance - is he suggesting that the rest of the UK will pay that in separate Scottish state too?
"State pensions are funded from current state revenue. This sophistry would make the Vote Leave campaign blush."
Donald Cameron, Scottish Conservative spokesman on the constitution, said: "For such senior SNP figures, including the Finance Secretary, to be suggesting pension rights will be unaffected in an independent Scotland is astonishing and blatantly inaccurate.
"It is clear that the SNP are all too happy to spread misinformation as they ramp up their plans for another divisive referendum."
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