The President of the Association of Secondary Teachers Ireland has said she is very surprised to learn that two errors have been identified in the Leaving Certificate calculated grades system.

At a press conference, Minister for Education Norma Foley said the errors are being rectified and the process is being rechecked, with a series of independent checks now under way.

Ann Piggott told RTÉ's News at One that the exams process is usually carried out very well, especially given this year was a new system and that makes the revelation of mistakes at this stage even more surprising.

Ms Piggott said it has been a long and difficult year for Leaving Certificate students and this finding may have an impact for college courses and the choices for some.

She said that 83% of marks this year went up or stayed the same, but many students that expected high grades were reported to be left disappointed.

She said that it is surprising it has been revealed at this stage.

Ms Piggott said that teachers had engaged in the process as a last resort and would have preferred the exams to go ahead.

She said that you "cannot replace the Leaving Certificate for fairness" and that students have competence in it and usually do as well or better than expected.

The Teachers Union of Ireland has said that the priority now is for students who were negatively impacted by the error to have it corrected. 

In a statement, the General Secretary of the union said it was regrettable that the error happened. 

Michael Gillespie said: "The priority must be to ensure that any student whose grades were negatively affected must now have the error made good. 

"While some students affected would in any event have already received an offer for the third level course that they wanted, others may not. For those who lost out on the course that they wanted as a result of this error, arrangements must now be put in place to make good their loss."

He also said that the error was a coding one and had nothing to do with the input of teachers in and schools. 

Meanwhile, the Irish Second-Level Students' Union has called on the Department of Education to ensure that students are communicated with immediately and given "the necessary information and support". 

Reuban Murray, President of the ISSU said: "This is going to have a very real and serious impact for a lot of students, we need to ensure all education stakeholders work together to make sure that the financial and mental impacts of these errors are mitigated and addressed because it wasn't the students fault that this happened. 

"We welcome the fact that these errors have been found - but now we need to address the impacts of them."