SCOTLAND'S exam body has rejected suggestions the pass mark for last year's Higher maths exam paper was lowered to ensure more candidates passed.

The Scottish Qualifications Authority (SQA) responded after its former principal assessor of maths said the pass mark was too low. The dispute broke out after examiners recommended last year's Higher maths exam should have a pass mark of 63 out of 130, which would have led to a 0.2% drop in the overall pass rate.

Instead, the SQA decided to lower the pass mark to 62, with the 1% drop meaning the pass rate increased. The principal assessor subsequently refused to attend a meeting to discuss longer term issues over his working practices and he had his contract terminated.

His departure was followed by five other senior examiners, who quit in protest at the manner in which he had been treated. After losing his job he attacked the SQA, saying: "Pass rates should go up and down, not always upwards as they have been doing in recent years."

However, the SQA said pass rates were routinely altered to reflect the changing difficulty of exams from year to year.

The Herald understands there were concerns the previous year's exam had been too easy and the subsequent paper too hard.

A spokesman for the body also revealed the principal assessor had originally approved the pass rate change.

"At the Higher maths grade boundary meeting in June 2012, it was very clear that some questions ... had proved to be more demanding than expected," he said. "SQA had received similar feedback about the exam from around 800 candidates and 80 teachers. As a result, the grade boundaries for Higher maths were adjusted on the basis of the evidence presented.

"The final grade boundaries for Higher maths in 2012 were mutually agreed and signed off by the principal assessor."