Plaid Cymru this week called for more research into the underachievement of black pupils. However, the Wales-only statistics also show attainment levels from key stages 1 to 4 nosedive most among children of white British descent.
Janet Ryder, Plaid's shadow education spokesperson, said: "Certain groups in our education system require more support, and we need to see if we have got the right structures in place across Wales."
The figures show that 63.3 per cent of black seven-year-olds passed core subject indicator (CSI) teacher assessments in 2005, compared with 81.5 per cent of white pupils. But by KS4, pass rates of black pupils had dropped to 21.6 per cent - but slightly less than the falling standards of white pupils at 37.5 per cent. The figures reveal that at age 15, Chinese pupils perform the best, with 61.4 per cent passing CSI teacher assessments.
Jane Davidson, minister for education, lifelong learning and skills, recently made the underperformance of black pupils a key target area for 2007.
Speaking at the recent Association of School and College Leaders Cymru conference in Llandrindod Wells, she said raising attainment levels of boys and pupils from black ethnic-minority groups was a "key challenge" in the Assembly government's agenda.
The figures show boys from both black African and Caribbean backgrounds do better at KS1 than girls in the same ethnic group. But by age 15, the girls slightly out-perform their male counterparts.
Estyn says there is not enough funding available to tackle underachievement by ethnic minorities. Most funding comes from the ethnic minority achievement grant.