Hundreds of pupils have seen their GCSE, AS and A-level results regraded due to errors made in the exam marking process.

The OCR exam board has apologised for the mistakes, which it said were made by examiners.

Chief executive of the organisation Mark Dawe said: "On behalf of OCR, I apologise unreservedly to the students, parents and teachers affected. I would like to reassure students taking their exams with OCR this summer that due to the rigorous new measures we now have in place, these issues cannot occur again."

People in maths teaching jobs and their students have already faced problems with GCSEs this year as the government looked to make the tests harder in an attempt to improve standards in the subject. Many more secondary education exams will be similarly changed over the coming years.

Mr Dawe said: "We have conducted extensive investigations into what went wrong. With the help of our most senior examiners, we reviewed all the relevant papers from last summer's exams and increased marks on a tiny percentage of papers as a result."

A statement by OCR said this mistake occurred as a result of human and process error caused by the transition to online marking. The board added the examiners involved are no longer associated with OCR.

In an effort to reassure pupils, parents, teachers and schools, the board said new and enhanced marker monitoring will be in operation for the summer 2014 exam period and additional analysis will be undertaken on candidate papers at the end of the marking process.

OCR said schools and colleges with affected students have been informed and the news has been passed on. It is unknown whether or not any of the students failed to achieve a university place with their initial lower grades.

As somebody in a secondary teaching job, who relies on exam boards to implement fair and uniform marking, how do you feel about this story?