BRITISH entrants to the international science Olympiads - intended to showcase the cream of the country's talent - are practically all from private schools.
At least four out of five of the UK physics team going to Taiwan for this summer's contest will be from the independent sector, organisers predict.
The maths and chemistry teams are also likely to be dominated by fee-paying students.
Organisers say private schools are hugely over-represented because they give a lot of personal tuition, have smaller classes and take the competition much more seriously.
Derek Bell, chief executive of the Association for Science Education, said:
"This is the sort of thing that we want a wider audience to be participating in, as it adds enrichment to the curriculum. But I suppose it reflects the pressures on teachers."
The first stage of entering the Olympiads is an exam in schools. The best entries are whittled down in a number of steps to a handful of pupils who receive intensive coaching. Only about 40 per cent of the 1,000 entries to the second round are from private pupils but the final selection is much more skewed.
Dr Cyril Isenberg, secretary of the British Physics Olympiad committee, said: "When you get further up the ladder to the higher rounds the percentage of publicschool students gets higher." Typically they will make up four out of the five final team members, he added.
A spokesman from the Royal Society of Chemistry, which organises the British team for the chemistry Olympiad, said entrants tended to be from private schools.
And Professor Adam McBride, who chairs the UK's maths Olympiad effort, said: "I would say students at public schools such as Westminster or Winchester obviously have a great advantage."
He said the maths team had problems recruiting state pupils. "We try our best to identify talent in those schools as early as possible and nurture those pupils. We periodically come across a really bright kid and the enrichment that our activities can provide is obviously just what they need."
Olympiads are held every year in a different country. Last year's maths contest was in Glasgow. This year teams, who receive training at universities, will travel to Japan for maths and Greece for chemistry.
Olympiads are also held in biology and computing.
Olympiads started in the Eastern Bloc, with the first maths contest held in Romania in 1959. UK teams have entered for some 20 years. Some countries take the competition more seriously than others, with the Chinese in particular giving teams tuition for years before the event and frequently winning.