More than a third of the pound;12 billion increase in school spending since 1997 has been swallowed up by teachers' pay, a TES analysis of official figures reveal.
A rise in teacher numbers, above-inflation wage increases and the introduction of performance-related pay have combined to add an additional pound;4.5bn to schools' costs.
The spiralling wage bill will alarm Chancellor Gordon Brown who has made it clear that he does not want spending increases swallowed up in higher public-sector pay.
Teachers' average salary increased by pound;7,000 to almost pound;29,000 between 1997 and 2002, the latest year for which figures are available, according to a parliamentary answer from David Miliband, school standards minister.
Teacher numbers increased from 399,000 to 420,000, during the same period.
The TES calculates this means a jump in the total pay bill from less than pound;12bn to more than pound;16bn, once extra payroll costs such as pensions and national insurance are included.
Ministers and local authorities blame rises in teachers' pay for contributing to last year's funding crisis. It is one of the reasons the Government has fought to limit the numbers reaching the top of the performance scale.
Concern about rising pay and heads using budget increases to employ more teachers were a driving force behind ministers' support for the workforce agreement, which encourages the use of cheaper assistants to take classes and do more than 20 administrative tasks previously done by teachers.
A survey by support staff union Unison found that the typical teaching assistant earns betwen pound;11,000 and pound;14,000 per year. The number of support staff rose from 136,500 in 1997 to 217,000 in 2002 and 242,000 in 2004. But this growth failed to halt the rise in teacher numbers which increased to 428,000 this year.