The programme, devised by the Qualifications and Curriculum Authority, has been criticised because of its cost. So far this totals pound;4.8 million - which works out at pound;1,087 per candidate. Despite the low take-up, the authority says the tests for nine and 13-year-old pupils are a success. It points to the fact that students in 10 countries have now registered for them - an increase from five when the tests were launched last November.
The test website receives 7,000 hits a day and more than 5,000 people have taken the Online Challenge maths test.
Just under two-thirds of candidates passed the tests, with up to6 per cent gaining a distinction.
One of the goals of the project is to provide an international comparison of performances.
Slovenian children are the latest to sit the tests. Spain, Malaysia, Saudi Arabia, and the United Arab Emirates have been involved since November.
Pupils read questions in English but are allowed to answer in their own language. The UK, theUS, Hong Kong, Australia and New Zealand were the original five countries.
Many of the UK children who have taken the tests here are from schools in poorer urban areas. The QCA said "very few" were from independent schools.
The numbers taking the tests are likely to surge as the Warwick University academy for gifted children expands. It describes them as "an ideal means of demonstrating ability for entry".