University graduates in Italy and Spain have been singled out as having particularly low basic skills by the Organisation for Economic Cooperation and Development (OECD) as it warned that the picture "fit" with high unemployment levels in the southern European countries.

In its annual report on education in richer nations, which for the first time measured basic skills such as literacy against education attainment, the OECD found that Italian and Spanish graduates were, on average, less skilled than high school leavers in the highest performing nations, Japan and the Netherlands.

On average across 22 OECD nations, 24% of people with a degree or a further education qualification reached a high standard – level four or five – on a standard literacy test.

But in Italy and Spain, only 12% of college graduates reached that level, placing the countries joint bottom in the rankings. In Japan, 13% of high school students reached level four or five, with 14% doing so in the Netherlands.

Andreas Schleicher, the OECD's director of education and skills, said: "If you are a high school graduate in Japan you have better skills than a university graduate in Italy and Spain. This is important. When you look at employment data, you might ask why so many graduates in Spain and Italy are unemployed. But when you look at the skills it fits. They are actually not particularly highly skilled."

But Professor Massimo Egidi, an economist and rector of LUISS Guido Carli, a private university in Rome, dismissed a link between the results and Italy's 43% youth unemployment rate for under 24-year-olds. The general joblessness rate in July stood at 12.6%, according to the country's national statistics body Istat.

"If it were true that there was high unemployment among young graduates in Italy because the quality was low, we would be full of companies in which Italians were taking on Japanese and Dutch [employees]. This does not seem to me to be the case … at all. The problem is something else entirely. The problem is a mismatch between demand and supply. It is not the quality of the supply, but the mismatch," said Egidi.

He said the university system was producing graduates "in the wrong proportions" for the labour market: too few engineers, for instance, and too many lawyers. Change was needed to smooth out this "huge imbalance", he added, but insisted quality, particularly among science graduates, could not be seen as a contributing factor to unemployment.

"The quality of the engineers, for example, and of physicists and biologists who have been educated in Italy is very high," he said. "And it is just as true that young people who don't find work in Italy do so easily abroad: in England, in America, and in Europe in general. You'll find many Italian engineers in Germany and many Italian economists in London."

Regardless of the debate over their impact on Italy, the OECD results would not come as a surprise to some. Italy and Spain came bottom of an OECD ranking for basic literacy and numeracy skills last year as well.

Duncan McDonnell, a senior lecturer at Griffith University in Brisbane, Australia, who taught undergraduates at the University of Turin for several years and was subsequently based at the European University Institute in Florence, argues that the way the Italian system works often has the unfortunate consequence of students not learning "any significant writing skills" during most of their time at university.

"One particular Italian problem which I found regarding literacy is this: most exams in Italian universities are still oral exams," he said. "Students get very little experience of writing during their undergraduate years until, right at the end, they are asked to produce a long dissertation. It is absolutely crazy: they have no preparation for doing so."