The revelation came as the Yorkshire education authority that has lost track of 33 pupils finally released a breakdown showing their age, sex and ethnicity.

And a study by the Home Office also released yesterday warned that the problem of forced marriages, in which girls as young as 13 are imprisoned in their home or sent to Pakistan and Bangladesh to marry against their will, was massively underestimated.

In a submission to the Home Affairs Select Committee, the Department for Children, Schools and Families said 2,089 pupils had gone missing in areas of particular concern.

The survey has been conducted over recent days after Children's Minister Kevin Brennan said last week that 33 pupils were missing in Bradford alone.

That sparked fears that many of the children would be from the city's South Asian communities and were being forced into a marriage.

But yesterday Education Bradford published figures that show that most of the missing children are of white British ethnicity – but also that the number had now increased to 34, of which 14 are girls. Eight are of primary school age and 26 are of secondary school age.

Parents are not obliged to disclose the ethnicity of their children but Education Bradford said eight were white British, one was a traveller, two were from white 'other' backgrounds, two were African, one was from a mixed background and only two were Pakistani.

Education Bradford managing director John Gaskin said: "There are a further 10 whose ethnicity has not been stated, however, we believe the majority are not of a South Asian origin.

"These figures change daily as children are found school places or we hear they have moved to other parts of the district or the country.

"However, this isn't an issue which is unique to Bradford and all local authorities report the figures of children missing from education to the DCSF."

Chris Keates, general secretary of teachers' union NASUWT, said: "The real issue of concern is that youngsters go missing from the system at all, rather than why this happens. The debate around forced marriages must not be allowed to distract attention from the fact that children are missing and at risk."

In a report for the Home Office, management consultant Nazia Khanum said the Government's Forced Marriage Unit dealt with 300 hardcore cases a year and she added: "If you follow the examples of rape and domestic violence, where only 10 per cent to 12 per cent of cases are reported, it's a reasonable assumption that it is the tip of the iceberg."