Children are risking chronic back problems in later life because some secondary schools have no storage lockers.

Chiropractors warn that bags carried around all day filled with heavy books, sports kit and packed lunches can cause lifelong problems.

The warning comes at the launch of National Back Care Week on Monday.

Ysgol Dyffryn Taf, Whitland, is in a minority because many of its pupils have access to lockers. This could soon change because the school wants to convert the locker area into a classroom.

Headmaster Robert Newsome confirmed that although some lockers would still be available there would be insufficient room to redistribute all of them around the school.

Mr Newsome claimed that a review of the system showed that children who had been allocated lockers did not always use them.

Parent groups across Pembrokeshire have regularly expressed concern at the absence of lockers, including the Friends of Pembroke School Association.

But association chairman Mary Hancock said when room was at a premium, classrooms must be given priority over cloakrooms.

"As a parent I used to think it was terrible that the children didn't have lockers, but as I became more involved I could see the logistics of it. After all, where would the school put them?''

Narberth chiropractor Judith Bird believes carrying the wrong bag with a heavy load could result in a generation of children with back problems.

She advised children to keep as fit and active as possible because this increased muscle strength.

"Unfortunately, children these days lead sedentary lives, but the best action they can taken to avoid back problems is to exercise and to keep as fit as possible,'' she said.

If children complain of muscle pain they should seek medical advice, she said. "Any pain needs to be investigated to prevent any further damage.''

PEMBROKESHIRE County Council claims there is no evidence that the carrying of heavy school bags harms pupils.

Its evidence is based on feedback from its health and safety group, which monitors accident prevention.

Four Pembrokeshire secondary schools provide lockers for their pupils. Ysgol Bro Gwaun, Fishguard; Sir Thomas Picton, Haverfordwest; Greenhill, Tenby, and Ysgol Dewi Sant, St Davids, all have lockers, although the provision at Sir Thomas Picton School is limited to certain year groups.

A county council spokeswoman said it was a matter for the head teacher to decide how to utilise the resources available to best effect.

In many schools there was provision to leave musical instruments or other items in a secure place, she explained.