Only a few drinks contain cyclamate
Young children should not be given more than a few glasses a day of fruit squash drinks that contain a particular sweetener, say experts.
The Food Standards Agency says that children aged four and below who drink more than a few cups a day of these dilutable drinks could exceed their recommended daily limit of the sweetener, called cyclamate.
The limits have been set because tests on rats suggested the chemical could damage their fertility.
Parents have been urged to check drinks they buy for either the name "cyclamic acid, "cyclamate" or "E952".
The sweetener is found in only a small number of brands in the UK, mostly lower-cost squashes.
Some cheaper fizzy drinks also contain it, but in much smaller amounts.
The Food Standards Agency recommends that children be given no more than three beakers (approximately 180 mililitres each) of these drinks per day.
It also says that less of the concentrate should be used to make up a drink for a child compared to a drink for an adult.
The problem was revealed after survey of parents revealed that children who drank squashes often consumed more than five beakerfuls a day, which would mean they exceeded their daily recommended maximum dose of cyclamate.
The bulk of squashes and diet soft drinks contained other forms of sweetener - only a few "budget" brands contained cyclamate.
These includes brands called "Jucee" and "GeeBee", an own brand squash manufactured for the Happy Shopper chain, and "Wells Whole Orange Squash".
None of the brands were found to exceed the legal limits set for manufacturers for cyclamate use.
However, the agency is now pressing the European Commission for these limits to be halved.
A spokesman for the British Soft Drinks Association, which represents the industry, told BBC News Online that it was in talks with the Food Standards Agency about potential cuts to the amount of cyclamate in soft drinks.
However, he said: "We don't think there is any reason for parents to be concerned about this advice from the Food Standards Agency.
"It's important to remember that these figures are calculated to represent a 'lifetime risk' - the risk of drinking this amount every day of your life.
"We think it's significant that these drinks tend to only be consumed by children."