The First Minister insisted the new institution would be “truly transformational” and was on a “different scale” from previous Scottish Government initiatives.
She spoke out the day after an implementation plan for the project, drawn up by Tesco Bank chief Benny Higgins, was published.
Scottish Conservative leader Ruth Davidson pressed her on the scheme at First Minister’s Questions at Holyrood.
The Tory said: “Yesterday the First Minister unveiled her plan to boost the Scottish economy with a new Scottish National Investment Bank.
“Of course that is a different thing to the existing Scottish Investment Bank, which is also different to the proposed business development bank and of course shouldn’t be confused with the SME holding fund or the capital acceleration programme or indeed the £0.5 billion Scottish growth scheme which has barely released a penny.”
The Tories submitted a Freedom of Information request about the investment bank to the First Minister’s office - but Ms Davidson said officials had written back “asking which one we were talking about”.
The Conservative said: “We replied ‘it is the same one that you announced in 2009, re-announced in 2013, that you announced again in 2015 and the one that John Swinney said you shouldn’t do after all in 2016’.”
She hit out: “First Minister, even your office didn’t seem to know the difference between the Scottish investment bank and the Scottish National Investment Bank so how can the public?”
Ms Sturgeon insisted however that the new project was “very different” to the other schemes the Conservative had mentioned.
She stated: “That is because we believe that we need to provide something and an ability to intervene on a scale and of a nature that is different to what has gone before.”
Ms Sturgeon continued: “Of course there is an organisation that sits within Scottish Enterprise called the Scottish Investment Bank, we want to do something now on a different scale and of a different nature.
“Yes we have considered this in the past and for various reasons have decided it isn’t the appropriate time to move forward. We have decided now is the time.”
She added: “We have had a range of interventions to provide financing for businesses to help them innovate, to help them export more. They have had some successes.
“But we look at the challenges facing our economy now, the need to catch up with productivity levels of other European countries in the way we have closed the gap with the rest of the UK, the need to grow the economy faster, and of course the need to prepare for the impact of Brexit that is being imposed by Ruth Davidson’s party on the Scottish economy.
“We think the time is right now to do that partly through the establishment of a Scottish National Investment Bank.”