Unauthorised absences showed in the school league tables for the first time reveal that the average for Wales is 1.7, compared to 0.9 per cent for England. Absenteeism for all causes in Wales is 11.0, whereas the figure for England is 8.7 per cent.
The figures have alarmed Welsh secretary John Redwood, who said: "I find it very worrying that in Mid-Glamorgan pupils on average miss more than one day a fortnight, and in South Glamorgan more than one-fifth of absences are unauthorised."
Mr Redwood is also unhappy with the GCSE results. The Welsh average for 15-year-olds gaining five or more A-C grades rose from 37 to 39 per cent this year, but Wales is still lagging behind England's 43.3 per cent.
Despite some improvement, it was still "a long way short of our targets, " he said, adding: "The spread of results, with the best LEA school obtaining 73 per cent and the worst only four per cent, is far too wide. More action is needed to lift standards in the worst-performing schools. I want the inspectors to use this material in their work."
Performances in both England and Wales are bettered by Scotland, which leads the way towards meeting national targets for exam achievements.
Dyfed and Powys achieved the best GCSE results in Wales with percentages of 45 per cent; Mid-Glamorgan came bottom of the league table with 30 per cent.
Clwyd and Powys had the lowest percentages for absenteeism for all causes - 8.8 and 9.6 per cent respectively. And Dyfed (0.7), Clwyd (1.0) and Gwynedd (1.0) had the lowest figures for truants.