Financial sweeteners to train in England make it a "challenge" to recruit Welsh-speaking teachers in Wales, a senior council officer claims.
Anglesey's head of learning Arwyn Williams told councillors Wales could not match the incentives.
Trainee teachers in England can get up to £32,000 in bursaries and extra pay, with lower qualifications needed.
The Welsh Government said it offered students up to £25,000 to become Welsh-medium teachers.
The issue came up at a meeting to discuss teacher sickness rates and the availability of suitable cover in one of the nation's Welsh-speaking heartlands, according to the Local Democracy Reporting Service.
Mr Williams was concerned that little over a third of teachers registered with the Education Workforce Council Wales were listed as speaking Welsh, let alone able to teach in Welsh.
He believed many prospective teachers were being lost because of greater rewards over the border.
"If a teacher wants to study at Bangor [University] they receive a certain levy, but if they go to England they receive much more," he said.
"So the incentive isn't there to encourage young people to study to become teachers through the medium of Welsh in Wales.
"That works against us as we try to attract more people to the profession.
"It's a real challenge and it's a message we've made clear to the Welsh Government."
In Wales, all prospective teacher training applicants must possess a GCSE B grade in Welsh or English and maths, with an additional C grade in science for primary school teachers.
However, the requirements are not as strict for English universities.
A Welsh Government spokesman said action was being taken to tackle the issue.
"There are generous financial incentives available for students to train to become Welsh-medium teachers, with up to £25,000 for those completing their Initial Teacher Education and going on to teach in Welsh," he said.