Huge numbers of young adults across the developed world are leaving formal education with poor literacy, numeracy and problem-solving skills, a major study has revealed this week.

The first international survey of adult skills ever conducted has uncovered deep disparities between countries, with the UK, the US, Italy and Spain coming low down in the league table for basic skills. Japan and Finland top the rankings.

The landmark study was conducted by the Organisation for Economic Cooperation and Development (OECD), which also compiles the highly influential Programme for International Student Assessment (Pisa) rankings. It assessed more than 150,000 adults aged 16-65 in 22 countries and was the first international survey to test people’s actual skills, instead of estimating them based on their educational backgrounds.

Around one in five Japanese and Finnish adults reads at the highest level, compared with just one in 20 in Italy and Spain, the study found. However, in all but one of the countries surveyed (Japan), at least one in 10 adults was proficient only at the lowest levels of literacy or numeracy. In other words, the report says, significant numbers of adults do not possess the basic skills needed to succeed in today’s world.

According to the OECD, the findings underlined the need to move away from a reliance on initial school-based education and towards a culture that promoted lifelong learning. It urged governments to maintain public investment in skills, even through difficult economic times, but also said that improving skills was “everybody’s business”.

“Countries need to address the tough question of who should pay for what, when and how, particularly for learning beyond school,” it said.

Andreas Schleicher, deputy director for education and skills at the OECD, stressed that the results did not reflect the performance of current governments but were more indicative of “the impact of cumulative policies over the past decade”.

This was seized upon by some politicians - including the Conservative-led coalition in the UK - who rushed to blame previous administrations for poor results.

But Alan Tuckett, president of the International Council for Adult Education, said that the problems experienced in many nations showed that “tinkering” with the school curriculum by successive governments had been problematic because it distracted attention from adult learning.

“This is powerful evidence that lifelong learning makes a difference for high-skilled and low-skilled alike, and that countries need a combination of good early education and a coherent lifelong learning programme,” he said. “What it demonstrates is a real need for investment in young adults and continuing investment across the (human) lifespan. There’s nothing inevitable about the results people get.

”(South) Korea is a spectacular example of what can be achieved when a country invests in lifelong learning.”

The East Asian nation is among the three lowest-performing countries when comparing the skills of 55- to 65-year-olds, but among 16-24 year-olds, it is second only to Japan, according to the OECD survey.

“In every decade, (South) Korea has been able to add (the equivalent of) two years of schooling to the entire adult population. Not just to the young but everybody,” Mr Schleicher said.

Nearby Japan was about three years of learning ahead of the average for the 16-65 age group, whereas Italy and Spain were about four years behind the average, he added.

Japan was praised for the equity of its education system, which allows access to education regardless of socio-economic background. Finland’s adult education system, meanwhile, was held up as an example for its focus on vocational education and apprenticeships.

Young people in England and Northern Ireland - who were surveyed to compile the UK results - were no better skilled than their grandparents, according to the report. The UK was ranked 14th in literacy and 16th in numeracy overall for 16- to 65-year-olds.

In many countries, including the UK, Germany, Poland and the US, social background had a major impact on literacy skills. It was also found that, in the majority of countries surveyed, significant numbers of adults had trouble using digital technology. Between 7 and 27 per cent of adults reported having no experience in using computers, or lacked the most basic computer skills, such as the ability to use a mouse.