The decision means more than 10,000 teachers are set to lose their jobs and many schools are bound to suffer a shortage of teaching staff, the union said.

"We believe this is a form of punishment by local administrative organisations after schools refused to come under their supervision," NTTU Council president Mana Sudsa-nguan said.

Mana shared his concerns with the ministry's permanent secretary, Khunying Kasama Varavarn, who will become the head of the Office of the Basic Education Commission (Obec) next month.

Initially, the government wanted to transfer responsibility for state schools from the Education Ministry to local administrative organisations in line with decentralisation laws. However, hundreds of thousands of teachers across the country strongly opposed the transfer plan. Finally, the government agreed that the transfers would take place on a voluntary basis only.

Most state schools did not agree to the transfer.

Mana blamed the problems surrounding the hiring of teachers on the Local Administration Department (LAD) decision to issue letters to all provincial administrative organisations and tambon administrative organisations, informing them that they cannot allocate budgets for state schools under the supervision of Obec.

Many local administrative bodies have paid more than 10,000 teachers on a contractual basis to help state schools cope with the shortage of teaching staff. This has been going on for three years, but could be stopped at the end of this month given the move by the LAD.

According to Mana, the LAD barred local administrative organisations from paying the teachers, citing the fact that the schools are not under the local bodies' supervision.

"Actually, the local administrative bodies can hire teachers by setting up learning centres inside the schools if they want to help," Mana said. He said relevant authorities should do something before the second semester starts in November. October is normally a school holiday period.

NTTU chairman Nipon Chuenta called on Obec to tackle problems faced by state schools such as a lack of teachers and budget shortfalls. Nipon also suggested that local administrative bodies should try and work closely with state schools instead of demanding immediate transfers. "When they are familiar [with each other], it's more likely that the schools will agree to the transfer," he said.

 "In fact, local administrative organisations can pay for teachers because such acts benefit their community," Kasama said.