The higher than usual number of mistakes in state exam papers was due to human error, a report has found.
Staff changes in the last 12 months combined with the demands of preparing large quantities of papers contributed to the errors, the State Examinations Commission (SEC) said.
"The SEC deeply regrets all of the errors in the 2013 papers and apologises to the candidates affected. Specific measures have been implemented in the marking process by the SEC so that candidates have not been disadvantaged as a result of these errors," stated the SEC.
It said the amount of mistakes was "unacceptably high" but claimed the rapid and unplanned departure of so many senior and experienced subject specialists (Examination and Assessment Managers) had resulted in a situation where over 30% of the current EAMs had been recruited in the last year.
The most significant mistake was on the Leaving Cert higher level maths paper two, which gave the wrong value for an angle in a trigonometry question which meant two answers were possible.
Minister for Education and Skills Ruairi Quinn said he was confident students were not disadvantaged and that measures had been put in place to prevent any repeat.
A statement from the Department of Education said: "The minister is concerned that errors can and do occur. But he is confident that the SEC has a robust system in place to respond to mistakes and in addition, through its annual reviews of the system, is constantly striving to minimise their occurrence.
"He has acknowledged the measures put in place by the SEC to ensure candidates affected by the mistakes were not disadvantaged in terms of the marks they achieved and is satisfied these have been effective. The key concern at all stages of the marking process was to ensure that candidates were not disadvantaged."
Mr Quinn has asked the SEC to brief him on the October review and said his department would engage with the SEC in relation to the recommendations in the report.
The statement added: "Having considered the SEC report's findings the minister notes the recommendations made to reduce the risk of errors occurring in future State examinations."