However, the exam authorities dispute the claim, insisting nobody is allowed to gain an unfair advantage by their actions.
Figures obtained by the Scottish Conservatives reveal that over the past four years, 35% of exam candidates who engaged in "malpractice" were given a ticking off, according to the party's education spokeswoman Mary Scanlon Highlands and Islands List MSP who said malpractice included using phones, notes or plagiarising.
She said the Scottish Qualifications Authority (SQA) released the statistics through Freedom of Information. They showed a total of 1264 pupils had been caught cheating in the past four years, 448 of whom were only warned.
That meant they faced no further action and were free to appeal their final grade.
Last year alone there were 324 penalties for malpractice, the highest in six years. Some 28% were cautioned, compared to 41% in 2011.
Ms Scanlon said yesterday the Scottish Conservatives wanted to see more done to ensure exam cheats do not get let off too lightly.
"It doesn't matter whether it's plagiarism, using a mobile phone or sneaking notes into the exam room; cheating in any form has to clamped down on. If it isn't, it completely undermines the vast majority of pupils who work incredibly hard in preparation for exams."
But Eric Martinez, SQA Director of Operations, said all security breaches were taken seriously and investigated, and candidates were made aware of the consequences of malpractice.
He stressed: "Warnings are only applied where candidates have gained no advantage from breaking the rules. This might include having a prohibited item, such as a mobile phone, in the exam room but not where it can be accessed."