The Organisation for Economic Co-operation and Development (OECD) delivered a report to the Scottish Government last year criticising elements of Scottish education, including the quango Education Scotland and exams body, the SQA.
Ministers had previously said they would do no more than fact check the report, but a freedom of information request to the SQA showed the exams body requesting and in some cases securing changes to the draft report.
The Scottish Government, however, said releasing their draft comments would prejudice relations between the “UK and an international organisation”, with the matter since referred to the Scottish Information Commissioner.
Education spokesperson for the Scottish Liberal Democrats, Willie Rennie, said it was clear the SNP had been “seeking a major rewrite” and had been “caught red handed”.
The former party leader called on Shirley-Anne Somerville to make a statement to parliament on the issue to “explain the inconsistency”.
He said: “The documents that Scottish Liberal Democrats extracted from the SQA reveal the extent to which there were efforts to change the report’s content and key themes from those at the top of Scottish education. They promised they were only fact checking but now we know they were fiddling the report.
“This is why we need a statement to parliament from the Education Secretary to explain the inconsistency between what they said was happening and what we have discovered since.
“It has all become clear as to why John Swinney didn’t want the report published before the election as he wanted time to change its content.
"The public deserve to know what hand the then Education Secretary had in this process.
"John Swinney's secret edit log should be open for teachers, parents and pupils to see. The new Education Secretary should come to parliament and commit to unravelling her predecessor’s web of secrecy."
Scottish Conservative MSP, Megan Gallacher, added: "Ministers clearly meddled in this report, which has diluted the independence of its findings."
A spokesperson for the Scottish Government said: “The OECD report is an independent review carried out by an independent body. The timing of its publication was determined by the OECD.
"The report, which was published in full on 21 June 2021, backed Curriculum for Excellence, and the Scottish Government has accepted its 12 recommendations.”
Work to reform Scotland’s exams system is underway, after the education secretary announced in August that the SQA would be scrapped and replaced, with Education Scotland having its inspection powers removed.
Professor Louise Hayward, of Glasgow University, is leading a group which will engage with stakeholders and provide advice to Ministers on how best to retain traditional exams in the new system.
In Holyrood in October, Ms Somerville said: “The issue of assessment and qualifications generates strong and sometimes conflicting opinions, however I am convinced that, given the experience and views expressed over the last two years, the time is right to signal that the Scottish Government supports reform of national qualifications and assessment," she told MSPs.
"The Scottish Government will consult on the purpose and principles which should underpin any reform."