Children from ethnic-minority groups are more likely to be marked down by their teachers in exams, the Education Secretary, Michael Gove, will say today.
He will make the point in a speech to head teachers this afternoon designed to support his plans to move away from teacher assessment in exams to traditional end-of-course tests.
He will tell the Independent Academies Association conference in London that externally marked tests are "fairer", adding: "The evidence shows that in teacher assessment of English achievement there is a tendency for ethnic-minority children to be under-marked and students from non-minority backgrounds to be more generously marked.
"With external testing there is no opportunity for such bias."
Mr Gove will also mount a robust defence of exam league tables in the wake of a report from exams regulator Ofqual last week showing they played a part in putting too much pressure on teachers to bump up marks.
He will praise their "clarifying honesty" – claiming that they have rescued schools from being judged on "hearsay and prejudice".