France's national health agency Anses says it has found chemicals in babies' nappies that exceed safety levels.
Tests found substances that are potentially dangerous to human health, including the controversial weedkiller glyphosate, the agency said.
Anses said its nappy tests were the first by any national health and safety body 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 take action.
What did they find?
The study was done on a number of different brands of single-use nappies available in the French market.
Some 4,000 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 likely introduced from contaminated materials, or as part of the manufacturing process.
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.
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 the World Health Organisation 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 United States, 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 "cooperate with the authorities to continue to meet the expectations of the consumers".