Instead, experts are blaming policy-makers’ failure to focus on high achievement over the past decade.

Wales took a hammering from the home nations in world rankings of 57 developed countries from the Organisation for Economic Cooperation and Development (OECD) released this week.

The results - leaving Wales ranked 28 in reading and 34 in maths - were so bad that the nation was on a par with former war zone Croatia.

But an in-depth look at the Programme for International Student Assessment (PISA) reveals the reason why Wales slipped so low in the rankings was due to a poor show by our brightest pupils against the best of the rest, not those on average ability or below.

The results also show that teachers in Wales are working harder to motivate pupils with good teaching practices, despite headteachers reporting a lack of resources on the scale of Azerbaijan.

Professor David Reynolds, an education expert at Plymouth University, said the abysmal figures were an indication of the Assembly government’s lack of support for high-achieving pupils.

“This is the result of the Assembly government looking towards the floor and not the ceiling,” he said.

“What we see is Wales not doing so badly against other countries when it comes to average students and those performing lowest.”

Professor Reynolds, who lives in Wales, also claimed that officials could not blame high levels of deprivation - or reliance on teacher-friendly policies - for the poor performance. “If you look at Scotland there is deprivation and teacher-led policies but it has still done very well,” he said.

“I would imagine England will be pleased that it has done better than Wales - despite its slump - because it is confirmation of its different direction in education policy.”

Scotland took the home advantage in the battle of the nations, out-classing England overall.

But the gloomy results for Wales, coming in bottom of the Brits, are a major embarrassment for Assembly government officials who had high hopes for Wales’s performance.

A source close to the government said that officials had believed Wales’s performance would be much better, and provide confirmation that its policy is on track.

“This will be a very big upset,” said the source.

“There was a firm belief that Welsh education policy changes over the past decade would lead to impressive improvements.”

Over the past year Steve Marshall, head of the department of education, culture and Welsh language, has made repeated claims that PISA 2006 results, the first Wales has taken part in, would be a true test of where the nation stood globally and not just in comparison with England.

Jane Hutt, Wales’s education minister, acknowledged the OECD rankings were a “valuable snapshot” of where the country stood internationally. But she dismissed the results as nothing more than a “league table” and said the most important thing was in analysing where to go next.

But a former special education adviser to the Assembly government said this week the results gave cause for concern. Professor David Egan, from the Cardiff School of Education at UWIC in Cardiff, said: “It was partly such concern that led in 2005 to the introduction of RAISE funding. In that sense, the PISA results confirm what we already knew.

“Now we need intelligent reflection on the implications. Simplistic solutions will not help. New actions may be required.”

There was also outrage among the Welsh teaching fraternity this week after Chris Woodhead, the former chief inspector of schools in England, said that Wales should reintroduce league tables.

Teacher callers to BBC Radio

Wales claimed that the poor results were indicative of “information overload” for both teaching staff and pupils in schools. Wales did better in science than in maths and reading, with an average result.

The results show science teaching is more pro-active in Wales, engaging and interesting pupils with more field trips and innovative, hands-on science experiences than anywhere else in the UK.

But complaints over a lack of resources at the chalk-face came home to roost in the results, according to Professor Reynolds.

The PISA study randomly tested 400,000 15-year-olds in their literacy of maths, reading and science from 57 countries worldwide between April and November 2006. Science was chosen as the main study focus that year.

In Wales, 124 secondary schools and 3,044 pupils took part in the study. The UK overall was ranked 17 in reading in a table led by Korea. Poland, Estonia and New Zealand were placed higher. In maths, Britain rated 24 in a table topped by Chinese Taipei.

An Assembly government spokesperson said: “Wales compares well with the other OECD countries in terms of science achievement, but naturally we want to improve our performance in both maths and reading.

“Our policies aim to enable all of our young people to achieve their potential but it takes many years to see the positive impact of reforms.

“We want to learn from what works in other countries and it is significant that what we are proposing for Wales mirrors what happens in countries like Finland.”

Wales trails against home nations

In Wales, 7.6 per cent of 15-year-olds who took part in PISA failed to make level 1 in reading, the lowest score, after a series of tests. This compares with 6.8 per cent in England. Scotland did the best in having more pupils meet the standard. (5.2 per cent). Pupils scoring level 5 in reading - the highest - came out as 6.4 per cent in Wales compared with Scotland (8.5 per cent) and England (9.2 per cent).

There was a similar story in maths, where the 6 per cent of Wales-based 15-year-olds failed to make level 1 - the same as in England. But just 3 per cent of Scots failed to make the mark. At level 6 in maths - the highest - the Scots came out top (2.7 per cent) and Wales was left trailing at a below-par 1.6 per cent.

In science, just 1.9 per cent of 15-year-olds in Wales made level 6 - the highest possible score - compared with 3 per cent in England.

UK’s PISA results, pages 16-17

Leader, page 28.