More secondary pupils have been put in ability sets since Labour came to power.
The news comes in the same week as the publication of a new report that concludes splitting children into sets can cause long-term damage to the education of summer-born and ethnic-minority children.
Data from the Office for Standards in Education suggests that the proportion of classes which are setted has risen from 34.2 to 38.6 per cent between 19961997 and 20012002.
The figure was uncovered by Nick Gibb, Conservative MP for Bognor Regis and Littlehampton.
Unfortunately for Mr Gibb, the statistics appear to undermine his claims that Labour has failed to boost the use of setting. The Labour manifesto for the 1997 election said that it would promote ability groupings in school because children were "not all of the same ability, nor do they learn at the same speed".
But Mr Gibb said he remained convinced that the Government had failed to honour its pledge. "If you compare the 19971998 figure which was 35 per cent to that for 20012002, the increase is only three percentage points, which is insignificant. And the amount of setting dropped by 0.2 per cent in 2001," he said.
The MP said that it was clear from the data that setting worked and had helped children from non-academic backgrounds and ethnic minorities.
However, a new report by two psychology lecturers at De Montfort University reaches the opposite conclusion.
Dr Claire Norris and Dr Paulo Aleixo say that several studies have found no evidence that ability grouping improves performance in either secondary or primary schools. They suggest the approach disadvantages children who are from non-academic backgrounds, ethnic minorities or are young for their year.
"Clearly, research evidence is mixed on the impact of ability grouping, be this setting, streaming or within-class grouping and does not seem to justify the current Government emphasis on it," they say.
Dr Norris and Dr Aleixo said that some pupils were being placed in ability groupings within classes from their first year of primary school. "A whole generation of boys, ethnic minorities and summer-born children could be failed by the age of five by an educational system that encourages ability grouping."
The Department for Education and Skills' guidance remains that setting should be the norm in secondary schools, and worth considering in primary schools, unless a school could demonstrate it is getting better than expected results through another approach.
A DfES spokesman said that, although the department encouraged setting, it did not promote streaming, in which pupils are divided into classes by ability and remain in them for all subjects across the curriculum.
'Ability Grouping in Schools: Attainment and self-esteem' is in Education and Health volume 21
Percentage of secondary classes that are set by ability:
Modern languages 59
Religious education 21
Proportion of secondaries which do not use setting: 13 per cent (Based on lessons observed by inspectors between 1996 and 2002)