Hundreds of cosmetic products sold in the UK and Europe contain ingredients that have been tested on animals, despite bans that outlawed such testing years ago, a new analysis has shown.

Banned tests were performed on ingredients used in products including moisturisers, lipsticks, sunscreen and hair conditioner, the analysis found, with more than 100 separate experiments performed on animals including mice and rabbits.

“European customers can’t assume the products they buy are not tested on animals,” said Thomas Hartung, an expert in alternatives to animal testing at Johns Hopkins University and one of the authors of the analysis. Even products labelled as not tested on animals may contain some ingredients that are tested on animals, he said.

At the heart of the issue are two sets of competing legislation. The EU ban on animal testing of cosmetic ingredients came into force in 2009. But another law regulating chemicals was introduced in 2007, placing the burden of proof on companies to identify and manage the risks linked to chemicals they manufacture and market in the EU to ensure worker safety.

This can include chemicals being manufactured exclusively for use in cosmetics, eclipsing the animal testing ban for cosmetic ingredients, according to the European Chemicals Agency (ECHA),

There has always been uncertainty about whether the chemicals legislation, the cosmetics legislation – or, indeed, the EU directive on animal protection, which says there should be no animal testing unless absolutely necessary – should be complied with, said Dr Julia Fentem, head of the safety and environmental assurance centre at the consumer goods group Unilever. “And that’s the difficulty companies find themselves in.”

This discrepancy has led some chemical companies to perform the banned animal tests on cosmetic ingredients, the analysis found. The researchers, who include a toxicologist from the German chemicals company Clariant, said that animal tests were carried out on cosmetics-only ingredients just to satisfy the chemicals legislation.

The researchers behind the analysis looked at hundreds of documents detailing chemical safety tests, which are publicly available on the ECHA website. They found that of 413 ingredients used exclusively in cosmetics, 63 were tested after the ban in the EU came into force. The post-ban ingredients were subject to 104 new animal tests, according to the paper published in the journal Alternatives to Animal Experimentation.

An ECHA spokesperson said the number of animal tests conducted as a result of chemicals legislation was likely to be lower but acknowledged that the agency has not ratified the research findings. To ensure worker safety, chemicals regulations require safety data, the spokesperson said. “Animal testing may be required – but only if no alternative tests are available.”

The agency does accept proposals to use alternatives to animal testing but a “very high percentage” of proposals do not give a “sufficient science-based justification” for their use, the spokesperson added.

In a recent high-profile case involving the German chemicals firm Symrise, ECHA ruled the company must carry out animal tests on two ingredients used solely in cosmetics to satisfy chemicals regulations, despite stiff opposition by Symrise that proposed using alternative methods. The company has since challenged the ruling at the European court of justice on scientific grounds.

The chemicals law “is being used to force companies, despite strenuous objections and even legal challenges, to commission questionable new animal testing as part of a bureaucratic box-ticking exercise,” said Troy Seidle, vice-president of research and toxicology at Humane Society International.

Peta’s science policy manager Dr Julia Baines said: “Shamefully, the animal tests requested for these two ingredients are just the tip of the iceberg.”

More animal testing of cosmetics-only ingredients is imminent, the researchers behind the analysis warned. “ECHA has already asked for new animal tests … involving thousands of animals and undermining the public’s confidence in the way the EU is upholding its animal testing bans,” said Dr Katy Taylor, director of science and regulatory affairs at the charity Cruelty Free International.

Scientists and campaigners have stressed that animal testing is no longer scientifically necessary to ensure cosmetic ingredient safety. “Lessons learned in animal-free safety assessment of cosmetics over many years can be readily applied to occupational safety assessment of ingredients without compromising human safety,” a spokesperson for the Animal-Free Safety Assessment Collaboration said.

Fentem said the European Commission should immediately suspend any further animal testing of cosmetics ingredients and re-evaluate what ECHA is asking companies to do. “The commission needs to be able to demonstrate to EU citizens how killing hundreds of thousands more animals to test cosmetic ingredients actually affords any better protection of workers and our environment, bringing forward evidence to show why modern non-animal safety science could not be used instead.”

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