The head teacher of a Kent secondary school that came near the bottom of national league tables says the government's figures are inaccurate.
Minster College's head teacher says the tables are unfair
Minster College, Sheerness, came last in Kent's Key Stage 3 results table and was one of the worst in the country.
Alan Klee said the figures did not include the grades achieved by students who took the test early.
The Department for Education and Skills (DfES) said other schools' results were recorded in the same way.
Just 19% of students at Minster College attained level 5 in English, 35% in maths and 25% in science, compared to the national average of 73% for English, 77% for maths and 72% for science.
But Mr Klee said the figures only showed the 267 students who sat the tests at Minster College and did not take into account the other 210 pupils aged 14 who took Key Stage 3 assessments before joining the school.
He added: "If they [the figures] were accurate I'd be concerned. They are not accurate and don't reflect the true picture. Therefore it does us damage which I don't think is justified.
"If you compare the two sets of figure you get a fair comparison. The results would be 45% for English, 60% for Maths and 49% for science.
"I wrote to the DfES to see whether we could claim the figures but they said legally we couldn't as they were taken at a separate school."