The Tories have called for the parliamentary business minister to answer questions at Holyrood on the involvement of special advisers in handling freedom of information (FOI) requests.
Conservative MSP Edward Mountain said Joe Fitzpatrick may have misled parliament when questioned on the issue last summer.
It follows research by lecturer and journalist James McEnaney which suggested that documents were removed from a FOI release at the request of a special adviser to Education Secretary John Swinney and Mr Swinney himself.
When asked whether requests were being screened for potential political damage by special advisers in June, Mr Fitzpatrick responded: “No, requests are all prepared by Scottish Government officials.
“Special advisers have a role in assessing draft responses for accuracy.”
Mr Mountain said: “We now know that the answers given by Mr Fitzpatrick to the Scottish Parliament are not true.
“The evidence suggests that special advisers are routinely involved in the freedom of information process for political purposes and John Swinney himself is suppressing documents when it suits him.
“Mr Fitzpatrick categorically denied this on the floor of the Scottish Parliament.
“Joe Fitzpatrick must return to the Scottish Parliament immediately and explain these responses.
“It appears this may well be a breach of the Ministerial Code of Conduct. It is entirely unethical for a Scottish minister to mislead the Scottish Parliament.”