Nicola Sturgeon has defended making handwritten notes for government policy which are then destroyed, saying there is “absolutely no substance” to claims it is to avoid scrutiny.

It emerged the First Minister’s office destroys her handwritten notes, rendering them unobtainable by Freedom of Information (FoI) requests.

However, Ms Sturgeon explained the notes are typed up into emails – which she said were “fully open to FoI legislation” and denied it was done to avoid the content of her memos being seen.

Asked about the report in The Times on a campaign visit to Aberdeen South, Ms Sturgeon said: “Just to be very clear here, when I write a handwritten note on a government submission, what happens is that my private office transcribes that note into an email that is then retained within the government in electronic form and fully open to FoI legislation.

“There is absolutely nothing different to what’s happened previously or untoward in any way, and I think opposition parties should stop trying to suggest otherwise.”

The policy has been in place since Jack McConnell was First Minister, Ms Sturgeon told the PA news agency, adding: “I’ve not changed it in any way, I haven’t introduced any new policies, my predecessors as first minister used exactly the same system, so I think other parties are trying to cast aspersions where there is no justification for doing so.”

She added: “If I write a handwritten note, my private office transcribes that note into an email. Otherwise, how would the policy official know what instruction I was giving on a government submission?

“That’s how the system works, it’s how I have dealt with government papers ever since I was in government in 2007 and, as we know, that policy has been in place since 2004-2005 so my immediate predecessors as first ministers used the same system and any insinuation – and I think it is an insinuation – that somehow I have changed the rules or created a system to try to evade scrutiny has absolutely no substance whatsoever.”

The Scottish Conservatives say they are prepared to report the First Minister to the records watchdog – the Keeper of the Records of Scotland – which can carry out a review of public bodies to ensure records are being correctly kept.

Conservative MSP Donald Cameron told the Times that the policy “reeks of secrecy and paranoia”, and said: “This is bizarre and potentially unlawful behaviour.”

In October, Ms Sturgeon was challenged in Holyrood for allegedly using an SNP email address for government business, to which she replied that she conducts the majority of government business on paper.

A Scottish Government spokesman said the First Minister has complied with the Public Records (Scotland) Act 2011 Act and added: “It is made clear that any emails and attachments relating to a decision, request or comment made by a minister must be filed appropriately by the relevant local policy areas.”