"We believe the new system is against the Constitution," Dr Kamolpan Cheewapansri, president of the Parent-Youth Network for Educational Reform, said.

Authorities introduced the new system without holding public hearings, even though the change was going to affect hundreds of thousand students, Kamolpan said. The lack of public consultation violated sections 59, 60 and 76 of the charter, she said. The new university-admission system, implemented this year, has caused havoc and forced the admission schedule to be repeatedly postponed.

The postponements were the result of the National Institute of Education Testing Service's failure to announce the O-Net (Ordinary National Educational Test) and A-Net (Advanced National Educational Test) scores on time. The scores were used as the main admissions criteria for the first time this year.

Kamolpan said the petition also addressed authorities' decision to let schools collect fees on top of tuition-fee subsidies from the state, which she said was unconstitutional.

The Constitution stipulates that children are entitled to 12 years of free education.

Chalermsak Jantorntim, acting secretary-general of the Office of the Ombudsman, accepted the petition and promised a review within 30 days. "If we find that the petition has grounds, we will forward the case to the Administrative Court or the Constitution Court," he said.

Kamolpan called on parents who wished to lodge a complaint with the Administrative Court to contact her network at www.parent-youth.net, saying: "We are willing to represent parents."