School's £500k spend on English pupils' bus transport 'broke rules'
A high school in Powys has broken council rules by using some of its delegated budget to subsidise the cost of transporting pupils from over the border in England, a report has shown.
In five years, Llanfyllin High School paid more than £500,000 on buses for pupils from outside its catchment area.
Supporters of Welsh-medium education said it has been damaging to the Welsh stream at the school.
Governors claimed council officers had known about the arrangement for years.
BBC Radio Cymru's Post Cyntaf programme found 187 pupils have benefitted from subsidised transport during this academic year, according to a report for Powys council's cabinet.
Of those, 38 are from other parts of north Powys while 149 come to Llanfyllin from the Oswestry area in Shropshire,
The council says this breaks finance regulations because the school budget is intended for education, not transport. Funding to transport pupils from another catchment should be provided by the PTA or by parents themselves, the report said.
The dual-stream school - which has more than 80% of pupils in the English stream and fewer than 20% in the Welsh stream - has more than 800 students on its register.
Supporters of Welsh-medium education said the move had become "a direct threat" as the number of subjects available in Welsh had decreased while the number available in English had gone up.
School governor and councillor Darren Mayor has resigned from his role as a member of the council's cabinet.
In a letter to the leader of the council he wrote: "At no point has the governing body ever hidden the use of its delegated budget and each year this transparency has been evident when budgets have been approved by the education department."
The cabinet said the school must comply with the rules by September.
In a statement, council leader Barry Thomas said "an independent is under way" but that "no further comment can be made until the review and any possible proceedings are complete".
The school's governing body will hold an emergency meeting on Thursday.