In March the Government announced an extra pound;400 million to fund more teaching assistants over the next four years. An estimated 1,200 primary learning mentors are working in 1,000 primary schools as advisers to pupils in the Government's Excellence in Cities programme.
A National Union of Teachers spokeswoman said it was impossible to estimate the numbers of parents helping out teachers in lessons at schools.
Teacher assistants' qualifications range from none to a PhD, according to the DFES. It was up to individual schools to specify what qualifications they wanted.
But teaching assistants, also called classroom assistants, will have to meet a uniform standard for training by the end of this year.
The DFES said a scheme has been launched to clarify what is expected of them. The New National Occupational Standards for teaching assistants have been developed by the Local Government National Training Organisation. The NVQs based on the new standards will be accredited by the Qualifications and Curriculum Authority this year.