Up to 16m adults are holding down jobs despite having the reading and numeracy skills of 11-year-olds, according to a government report.

The report also claims that despite an investment of billions, the government's Skills for Life scheme has done little to improve the quality of adult literacy and numeracy teaching.

MPs on the Commons Public Accounts Committee claim that almost £6bn will have been spent on the scheme by 2010. However its first few years have delivered little evidence of improvements in the provision of literacy and numeracy classes in colleges or in on-the-job training by employers, the committee said.

According to the report, 12 million people in employment have Level 1 literacy skills and 16 million Level 1 numeracy skills - equivalent to what is expected of an 11-year-old. The number of people under-skilled in both aspects is unknown.

It highlights poor quality of provision and teaching as a major reason for lack of progress.