A school in Swansea is considering tagging its pupils because of a shortage of assistants who can supervise lunch breaks.
Children would wear tags which would sound if they left the school
The idea is for children at Lonlas Primary to wear the tags all day, with a buzzer sounding if they leave.
The shortage of assistants has been put down to low pay and unfavourable working hours.
Sara Reid, the Deputy Children's Commissioner for Wales, said she was concerned by the plans.
"I understand that schools need to worry about the safety of the children but we are concerned about the effect this is having on the human rights of children," she said.
"There is a need to supervise we know and to make sure that the children are safe."
The head teacher at Ysgol Gynradd Gymraeg Lonlas, Dyfrig Ellis, picked up the idea from an IT conference in the Netherlands and has already begun talks with a Dutch company about the tagging scheme.
"On one hand the tagging system does appear extreme but I believe that it's an option I have to consider when the safety of pupils is in question," he said.
Welsh teaching union Ucac has called for a change in the current system under which the responsibility for filling the posts of lunchtime assistants falls in schools and their governors.
The union wants local authorities to take over the role.
Head teacher Dyfrig Ellis says tagging is an option he has to consider
"We sympathise with the local education boards and with the heads of schools as they seek for supervisors," said Dilwyn Roberts Young from the union.
"But we must stress that it's the boards' responsibility, not only the heads, which is unfair."
Daphne Weekes, has been a lunchtime assistant for five years at the Welsh-medium school, which has about 350 pupils aged up to 11 years.
"It's not hard, you do need patience," she said.
"I'm like a mother to the kids making sure they eat their dinner."
Chairman of the school's governing body Robat Powell said: "All that has been agreed is that we will meet the company and the local education authority to discuss a possible pilot in the school. We would evaluate it.
"We are concerned not to add to the teachers' workload and we would have to find out the exact details of the plan."
Mr Powell said he believed the tags would be worn on pupils' wrists, but added: "That is something we will have to find out from the company.
"The idea is that if a child walks off school premises the electronic system would pick this up and it would register in a central control room."
A spokeswoman for the Department of Education said she did not know whether such a scheme had been piloted before.
She said: "It is really a matter for schools to develop policy that suits their needs.
"It is about local solutions for local problems."