Schools in Ireland are more selective in admitting and grouping students than the international average, the OECD report on education shows.
Earlier this week the Minister for Education, Mr Dempsey, convened a crisis meeting of Limerick schools to discuss the enrolment situation in schools in the city.
This followed allegations that some schools in the area were operating a policy of "educational apartheid".
And a survey of school principals contained in Education at a Glance 2004 shows that Irish schools place more emphasis on selecting students than schools in most other countries.
According to the report, while Spain and Sweden were among the least selective countries in this regard, Ireland, Hungary and Italy were among those which operated most selection, as well as grouping according to subject choice and preference.
Enrolment in third-level education, which covers both university and vocational programmes, increased by more than 20 per cent in Ireland during the period from 1995 to 2001, the report says.
Australia, Finland, Mexico and the UK also saw the level of enrolment in tertiary education increase by a similar figure.
However, others such as the Czech Republic, Greece, Korea and Poland saw enrolment increase by more than 50 per cent.
In Australia, Canada, Germany, Hungary, Ireland and the United Kingdom the benefit of a third-level education in terms of earnings rose by between 6 and 14 per cent between 1997 and 2001.
In all countries with available data, the rate of return from investing money in a university course was significantly higher than the cost of undertaking that course, the report states.
But it is significantly lower for those who enter tertiary education later in life.
However, while some countries have succeeded in increasing the numbers of lucrative foreign students coming to study, in Austria, Ireland, Switzerland and the United States increases in the share of foreign enrolment ranged between only 8 per cent and 13 per cent.
Women still earn less on average than men in all OECD countries, whatever their level of education.