Food safety experts have advised parents to eliminate a series of additives from their children's diet while they await the publication of a new study that is understood to link these ingredients to behaviour problems in youngsters.

The latest scientific research into the effect of food additives on children's behaviour is thought to raise fresh doubts about the safety of controversial food colourings and a preservative widely used in sweets, drinks and processed foods in the UK. But the Guardian has learned that it will be several months before the results are published, despite the importance of the findings for children's health.

Researchers at Southampton University have tested combinations of synthetic colourings and preservative that an average child might consume in a day to measure what effect they had on behaviour. A source at the university told the food industry's magazine the Grocer last week that their results supported findings first made seven years ago that linked the additives to behavioural problems, such as temper tantrums, poor concentration and hyperactivity, and to allergic reactions.

Both studies were conducted for the Food Standards Agency.

The latest results were considered by the FSA's Committee on Toxicity of Chemicals in Food (CoT) in a closed meeting on March 20. The CoT, whose meetings are usually open, noted "the public health importance of the findings", but the results will not be released to the public or acted on until they have been published in a scientific journal, a process that will take several months.

The FSA and Professor Jim Stevenson, who led the project, said they could not discuss the results before then. It took the CoT more than two years to release its views on the earlier research because it was waiting for publication in a scientific journal. Independent experts say that consumers should consider removing these additives from their children's diets now. The colours, tested on both three-year-olds and eight-to-nine year olds in the new study, were tartrazine (E102), ponceau 4R (E124), sunset yellow (E110), carmoisine (E122), quinoline yellow (E104) and allura red AC (E129). The preservative tested was sodium benzoate (E211).

Although these additives are widely used in the UK and are approved as safe and legal by the EU, some of the colours are banned in Scandinavian countries and the US. Campaign groups such as the Hyperactive Children's Support Group have argued for years that children's behaviour is improved by removing artifical colourings and other additives from their diets.

Vyvyan Howard, professor of bio-imaging at Ulster University and one of the experts on FSA's additives and behaviour working group, said it was important that the new research was published in a scientific journal but that consumers had a choice. "It is biologically plausible that there could be an effect from these additives. While you are waiting for the results to come out you can choose not to expose your children to these substances. These compounds have no nutritonal value and I personally do not feed these sorts of foods to my 15-month-old daughter."

Another member of the working group, Dr Alex Richardson, the director of Food and Behaviour Research and senior research scientist at Oxford University, said: "There are well-documented potential risks from these additives. In my view the researchers had done an excellent piece of work first time round and there was enough evidence to act. If this new study essentially replicates that, what more evidence do they need to remove these additives from children's food and drink?"

The FSA has been considering the safety of these additives since 2000, when it received the results of the first trial known as the Isle of Wight study. That research concluded that "significant changes in children's behaviour could be produced by the removal of colourings and additives from their diet [and] benefit would accrue for all children from such a change and not just for those already showing hyperactive behaviour or who are at risk of allergic reactions."

The CoT, however, decided in 2002 that this study was inconclusive - although parents, who did not know whether their children were on a placebo or not, observed significant behavioural changes in those given the additives, other observers did not find the same changes when children were assessed in a clinic using computer games to measure inattention. So the FSA set up the new study to provide conclusive evidence, with a working group of independent experts giving advice on how best to design it.

If the findings of the new research do confirm the Isle of Wight work, "the implications would be enormous", said Tim Lang, professor of food policy at City University, in London. "The stakes are very high; these are additives that children have been exposed to for years. I can understand the FSA wanting to be sure no one can accuse it of breaking scientific protocols but these findings need to come out quickly," he added.

A spokeswoman for the FSA said the agency was "committed to handling science in the proper scientific way" and hoped the findings would be published in a matter of months. She added that all the additives involved "are approved for use in the EU and are safe".