More than 1,000 students who submitted portfolio work for the Junior Cert civics exam were not awarded any marks for it because of striking similarities in their work.
The Department of Education confirmed yesterday that marks given to 1,300 students in civic, social and political education (CSPE) were based on written work only, because of concerns over the portfolio work.
The Department declined to say the students had cheated, but expressed "grave concern" over the portfolios.
This morning over 60,000 students receive their results and in line with the Leaving Cert, they are broadly positive - despite the days lost due to the ASTI strike earlier this year.
The Department refused to elaborate on why so many students could have handed in similar work.
One explanation was that some teachers made too much of an input into their students' work - so pupils then ended up submitting similar work.
The Minister for Education, Dr Woods, said last night that during the examination of portfolio work, examiners noted "significant similarities" between the work of several candidates.
He said the Department believed it was not clear there was a "premeditated attempt" by candidates, or any other party, to breach regulations.
"None the less, the degree of similarity in the work of candidates in some instances presents a difficulty in relation to the validity of any assessment of the work in question," he said.
The schools involved have been informed. More than 58,000 candidates sat the exam this year.
Failure rates were down this year in the Junior Cert. Ordinary level maths had an 11.5 per cent failure rate. This follows an almost 17 per cent failure rate in ordinary level maths at Leaving Cert. The failure rate in ordinary level French was also high, at 15 per cent.
The president of the ASTI, Ms Catherine Fitzpatrick, urged students to celebrate their results in an "appropriate manner".
"It is understandable and right that students should celebrate achieving this certificate. However, I would urge all students and their parents to ensure that today's celebrations do not end in tragedy," she said.
Ms Fitzpatrick also called on publicans and those running night entertainment to be mindful of the Intoxicating Liquor Act which places an onus on publicans to ensure intoxicating liquor is not sold to teenagers.
Dr Woods welcomed the call of the Vintners' Federation of Ireland to its members not to serve alcohol to those celebrating the results.
He said: "The results should be a source of pride for students, their parents and teachers - not to be undermined by the negative outcomes of alcohol abuse."
Dr Woods said the grades achieved by candidates taking ordinary level were better than previous years, with more honours and less fail grades.
He added: "It is encouraging to see that, in science, there is an overall improvement in the percentage of candidates achieving honours in ordinary and higher levels."
An Internet service is available for students to get their results from 4 p.m. today on www.examinations.ie
Students will be able to access their results by using a PIN number and their examination number.