Nicola Sturgeon said while Westminster is yet to confirm how much senior citizens on the new single tier pension will receive, it is estimated that payments could be about £155 a week.
But she said those receiving the single tier pension - which is due to come in in 2016 - will get £160 a week if there is a Yes vote in September’s independence referendum.
Earlier this week shadow Scottish secretary Margaret Curran claimed leaving the UK would be a “leap in the dark” for Scots who rely on pensions and other benefits.
But Ms Sturgeon insisted: “Only independence will deliver the powers we need to bring about a fairer deal for our pensioners and ensure we have a pension system that is right for Scotland.”
The SNP has already pledged to bring in a “triple lock” guarantee for pensions if there is a Yes vote, meaning pensions will rise annually in line with either inflation or earnings, or by 2.5%, depending which is highest.
Ms Sturgeon said: “With independence, new pensioners receiving the single tier pension will get £160 per week. But while the Scottish Government has confirmed this rate, the Westminster Government is refusing to come clean on how much the single tier pension will be in 2016.
“Looking at what the UK Government has said, we estimate that new pensioners in Scotland will be around £5 per week - or £260 a year - better off than they would be as part of the UK.
“With the full powers of independence we can also introduce a triple lock on the state pension to keep pace with the cost of living. And we can establish a state pension age that meets Scotland’s needs - with an immediate review of Westminster’s plans to increase the retirement age to 67.
“Scotland has paid more tax per head than the rest of the UK for each and every one of the last 30 years - and spending on pensions is more affordable for Scotland. Figures show that 38% of Scottish tax revenues are spent on social protection, including pensions, compared to 42% for the UK as a whole.
“The Westminster parties cannot get away with hiding the truth from Scotland’s older people. They must come clean about how much our new pensioners stand to lose as part of the UK.”
But the pro-UK Better Together campaign has already argued that spending on benefits and pensions is higher in Scotland than the rest of the UK.
A report from the campaign group said: “Overall, Scotland spends £60 per head more on pensions and benefits than the UK as a whole - this is based on individual need, but the overall costs are also reflected in the costs of provision. We spent more on pensions, because we have proportionately more older people, and on things like invalidity benefit because of our industrial history.
“’The number of Scottish pensioners will grow from 1 million to 1.3 million over the next 20 years. In Scotland we have a shrinking working-age population. This puts real pressure on the cost of pensions but also reduces the budget available for benefits.”
Speaking on behalf of Better Together, Jackie Baillie, Labour’s Holyrood spokeswoman for social justice, equalities and welfare, said: “The Nationalists have no credibility on pensions given their plans rely on Scots dying earlier than people in the rest of the UK. The SNP’s focus should be on improving people’s wellbeing and life expectancy here in Scotland, rather than always blaming someone else.
“By saying no thanks to separation we can guarantee the pensions of a million Scots by pooling and sharing resources with 63 million people in the UK rather than five million in Scotland.”
A spokesman for the Department for Work and Pensions said: “The Triple Lock guarantee was introduced by the UK Government and has safeguarded the value of state pensions for hundreds of thousands of Scots.
“In the future, spending on pensions along with benefits and other public services in Scotland will be more affordable as part of the United Kingdom because the broad shoulders of the UK will spread risk and provide a crucial safety net against Scotland’s ageing population.”
UK pensions minister Steve Webb said: “It’s easy to promise people higher pensions and earlier retirements when you don’t give any consideration to how it’s going to be paid for or what other public services will have to suffer as a result.
“Until the pro-independence movement can explain how all their various promises will be funded, they will always lack credibility.”