The new scheme is being launched by First Minister Rhodri Morgan and Sports Minister Alun Pugh at Barry leisure centre in south Wales on Thursday morning.

Ten local authorities took part in a pilot project over the Easter break, and it is now being rolled out across Wales for the summer holidays.

Mr Morgan has described the scheme as "an exciting opportunity".

"It has enormous potential to boost participation in sport and physical activity, improve health, cut down obesity and impact on families who don't have big incomes keep children amused in the holidays," he said.

Under the scheme, children under 11 must be accompanied by a paying adult, but still swim for free.

Over Easter, local authorities including Cardiff, Gwynedd, Swansea and Ynys Mon tested the project, which is receiving �2.5m from the Welsh Assembly Government this year.

Free swimming for children was piloted by Glasgow City Council, where it has proved successful.