Wales is falling behind the rest of the UK in reading, maths and science, an international study shows.
The nation's teenagers scored lower results on average in each of the three subjects than their counterparts in England, Northern Ireland and Scotland, according to the latest Programme for International Student Assessment Tests (PISA) tests.
Scotland leads the way in the UK in maths and reading, while England is ahead in science.
The figures, published by the Organisation for Economic Co-operation and Development (OECD), show that 15-year-olds in Wales scored 468 points on average, compared with 498 in Scotland, 495 in England and 487 in Northern Ireland.
In reading, Scotland scored 506 points on average, England scored 500, Northern Ireland 498 and Wales 480.
In science, England's average points score was 516, compared with 513 in Scotland, 507 in Northern Ireland and 491 in Wales.
The OECD report concluded that for each of the three subjects, "performance in Wales was lower than the rest of the United Kingdom".
Tory Assembly Member and shadow minister for education Angela Burns said in October that Labour First Minister Carwyn Jones promised improvements in Wales's PISA rankings.
She said it was only fair that people expected him to deliver, despite recent attempts by Labour ministers to talk down the significance of the results.
She said: "Labour has been responsible for education in Wales for 14 years and it is time we saw significant improvements so young people in Wales can compete in the global race."
Nigel Smyth, CBI Northern Ireland director, said: "No issue matters more to the Northern Ireland economy over the long term than the quality of our education system.
"Increasing our focus on maths and English will result in better performance, but we also need to support schools to create vibrant environments for developing the behaviours young people need for success in life and work. It's clear from the findings that resilience in young people is a predictor of high performance."