Oxford City Council has been forced to offer its free swimming scheme to all under-17s, no matter where they live, to avoid falling foul of European law.

Last Saturday, the authority introduced free swimming for city children at municipal pools, but the European Court has ruled it is unlawful for a public authority to offer discounted prices to users on the basis that they live in a particular area.

The ruling comes after a council in the Italian capital, Rome, offered discounts to museums and other state-provided facilities to those living in the city, but levied a different charge on outsiders.

The European Court ruled this two-tier pricing structure was unlawful, which means Oxford's £125,000 free swim project is now open to anyone aged 17 and under, regardless of where they are from.

In a report shown to councillors yesterday, Jeremy Thomas, the city council's legal adviser, said: "If the council stipulates that to take advantage of the free swimming children must live at an Oxford address, we could be held to be acting in a way the European Court deems to be unlawful."

The European directive has prompted parallels with the city's free bus travel scheme for pensioners, which also started on April 1.

That scheme allows Oxford's over-60s to travel for free on journeys within the city boundaries, but not outside.

City council leader Alex Hollingsworth said: "This is an interesting matter of principle and I have to say I don't see the difference between swimming pools and buses on this particular issue.

"How is it that our concessionary bus fare scheme is only for the people of Oxford and not for those outside?

"There is an argument that by making swims free, it is something that is reducing the amount of income coming into the city.

"But for years and years people from Hinksey, Botley and Kennington have been coming in and see Oxford as much their city as the people within the city boundaries."

Uptake of free swimming is expected to lead to a 90-minute restriction on the amount of time individuals can spend in the pool.

The City of Oxford Swimming Club has already expressed its opposition to the free swimming scheme, claiming it would have an adverse effect on subscriptions.

However, city councillor Mary Clarkson, executive member for leisure, said: "This is a great way for children, young people and their friends and families to get fit and enjoy themselves."