EXAM papers for this year's Higher English have had to be replaced amid concerns some questions could have been leaked.
The Scottish Qualifications Authority (SQA) said a new version of one of the two exam papers was sent out to schools and exam centres last month as a "precautionary measure".
A spokesman said: "A potential issue with one of the Higher English question papers was identified. We made the appropriate adjustments and a new paper was distributed to centres. Our chief invigilators have been informed."
Tens of thousands of candidates across Scotland will be sitting the exam on Thursday.
A spokesman for the Educational Institute of Scotland (EIS) teaching union said: "Where there is doubt over an element of an examination paper, the sensible option is to replace that section of the paper.
"The most important consideration is that no pupil is unfairly advantaged or disadvantaged, so that the exam can deliver a fair measure of each pupil's level of attainment.
"Clearly, there will have to be a thorough investigation into the circumstances that led to this situation, but the most important issue in the short term is to ensure that any issues with the paper are rectified."
The SQA did not say just how much of the exam paper had to be changed. Schools are expected to store papers securely until shortly before each exam.
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules here