Teacher assessments of 11-year-olds' attainment in maths and English released this week are broadly in line with national test results.
But the Government statistics may not be enough to reassure the many schools who believe they were marked down in this year's English tests.
The alleged misgrading was largely confined to the writing paper. The teacher-assessment figures cover English overall but do not distinguish between reading and writing.
John Bangs, the NUT's head of education, said the teacher-assessment could help resolve the marking dispute if they were broken down.
But he welcomed the fact that the assessments were so close to the test results.
"The Government's expert group said teacher assessment was not reliable enough to replace tests yet," he said. "This shows they were wrong."
The teacher assessments were the same or one percentage point different to the tests in terms of the proportion of pupils, boys and girls, reaching levels four or five in English and maths. But there was more variation in science, where 86 per cent of pupils had reached level 4, compared with 88 per cent in the tests, and 38 per cent had reached level 5 compared with 43 per cent in the tests.
This is the first year that teacher assessment has been the sole means of measuring 14-year-olds' progress, following the abolition of the key stage 3 national tests last autumn.
The assessments showed that 77 per cent of pupils reached the expected level 5 in English, up a percentage point from last year's teacher assessments.
In maths, 79 per cent reached level 5 - the same as last year - while in science the proportion was up by two points to 78 per cent.
The NASUWT said the KS3 figures were a "good news" story. The schools minister, Vernon Coaker, said: "Test results show thousands more children are getting the firm foundations they need in English, maths and science than in 1997, and today's teacher assessment figures back this up."
But the Liberal Democrats said it was "shameful" that more than a fifth of 14-year-olds were still failing to reach the expected standards in English and maths.
The Tories said the figures showed there was still a "real problem" with the first years of secondary school.