Crash swimming courses may not teach children adequate skills, warns the Royal Dutch Swimming Federation on Wednesday.

Ellen Julius, communications and PR officer, reportedly told the Telegraaf that the so-called ‘turbo’ courses – which can take just weeks rather than months to teach swimming proficiency – may not be enough.

‘You can learn the basics, but coordination between the arms and legs requires time,’ she said. ‘In addition, a child only really learns to swim well by repetition.’

The body, known as the KNZB in Dutch, is concerned about an apparent rise in parents choosing to put their children into crash courses rather than spending months carting them to and from weekly lessons.

A spokeswoman from the national swimming diploma organisation, the NRZ, told the Telegraaf that currently anybody can offer a swimming diploma since they are not regulated by law.

Press officer Marjolin van Tiggelen reportedly said: ‘You can just get a child to jump into some water one morning, swim back and forth three times, design a bit of paper and say: here’s your diploma.’

This is not the first time concerns have been raised about swimming courses. In May, two teachers and three swimming instructors were ordered by the courts to undertake 120 hours of community service for a lesser form of manslaughter, after a nine-year-old Syrian girl drowned during a school swimming lesson.