In a letter to Monmouthshire County Council's (MCC) planning committee, concerns were voiced over the development having a "detrimental effect" on pupils enrolling at the school.
The unnamed author of the letter said: "We are concerned that such a highly visible and inappropriately sited development in such close proximity to the school would be likely to have the detrimental effect of dissuading potential parents from sending their children to the school - it would not create a very positive impression on approaching Dixton Lane for parents of young children.
"Any reduction in pupil numbers could result in a reduction in the staff employed."
Further concerns included excess traffic and limited parking.