Prayut Petchkhun, deputy spokesperson for the Office of the Attorney General, said on Tuesday morning that the school has sent a letter refusing to talk to parents, saying it was ready to fight the case in court.
The case of child abuse at the school has sparked public anger for months, while 13 teachers have so far surrendered to police.
Police have found evidence of 58 students being physically assaulted by teachers, some of whom are already serving a prison sentence.