France's national health agency Anses says it has found chemicals in babies' nappies that exceed safety levels.
Tests found levels above safety thresholds for substances potentially dangerous to human health, and lower levels of others including the controversial weedkiller glyphosate.
Anses said its nappy tests were the first of their kind in the world.
It has called for rapid action "considering the possible risks these chemicals may pose" to babies.
France's Health Minister Agnès Buzyn said there was "no serious or immediate risk" to babies' health.
"Obviously we should continue putting nappies on our babies. We've been doing that for at least 50 years," she told AFP.
But a joint statement by the health, finance and environment ministers said the government had given nappy manufacturers 15 days to come up with an action plan aimed at getting rid of the toxic substances.
Ms Buzyn said the government would accept a delay of up to six months for production methods to change.
What did they find?
The study was done on a number of different brands of single-use nappies available in the French market.
Some 4000 such nappies might be used in the first three years of a baby's life, Anses said.
The report did not name the brands it tested, beyond saying it was representative of the French market. Some nappy brands available in France are also sold in other countries.
Under what it called "realistic use" conditions, it "detected a number of hazardous chemicals in disposable diapers that could migrate through urine, for example, and enter into prolonged contact with babies' skin," the agency said.
Some of the chemicals were added intentionally, "such as perfumes that could cause skin allergies", Anses said.
But others were probably introduced from contaminated materials, or as part of the manufacturing process plan.
Among the chemicals found in excess of safety thresholds were the perfumes Lilial and Lyral, and aromatic hydrocarbons, dioxins and furans.
Glyphosate was also listed in the agency's report, at lower levels.
Why is glyphosate controversial?
Marketed under the name Roundup in the US, it is widely used but has been a frequent target for health and environmental campaigners after a World Health Organization study classified it as "probably carcinogenic".
But it remains the most widely used herbicide in Europe, as EU officials do not agree that the product is a carcinogen. Yet in the US, a groundskeeper who sued a maker of the chemical was awarded millions in damages by jurors who agreed it had contributed to his terminal cancer.
The weedkiller is due to be banned in France by 2021, and its presence in nappies made headlines in the country when the report was released.
"Anses recommends eliminating the chemicals found in single-use baby diapers, or reducing them as much as possible," the agency said in a statement.
That includes stopping the use of all perfumes, it said.
It is also calling for tougher regulatory measures at an EU level - something which the French government said it was pursuing in the wake of the report.
The umbrella group for makers of French hygiene products, Group'hygiène, released a statement about the report, saying more than three billion nappies were used every year without any adverse health effects. A range of quality and safety controls were already in place, it said.
The group's managing director, Valérie Pouillat, said manufacturers would "co-operate with the authorities to continue to meet the expectations of the consumers".
After the French report was released, Belgian consumer group Test Achats (also known as Test-Aaankoop) released results of its own nappy testing, due to be published next month.
It found that in Belgium, there were some chemical traces, but "no need to worry".
"The differences in results … are probably explained by the fact that the substances researched are not identical, and that the brands of diapers differ from one market to another," it said.