Five children’s toys on sale in Britain analysed in a Guardian investigation have been found to contain asbestos.

It is illegal to sell products containing any quantity of asbestos fibres in the UK because of the long-term risk of cancer and respiratory problems if they are inhaled.

More than 30 toys have been withdrawn from sale by retailers since the Guardian first reported on asbestos being found in toy sand in January, prompting a wave of testing and recalls.

However, tests commissioned for the investigation suggest there are still products on offer that pose a potential risk to health.

The discovery raises fresh doubts about the UK safety regime’s reliance on self-reporting, and exposes regulatory gaps between different European countries, as similar items had already been recalled in the Netherlands.

The latest round of laboratory analysis looked at six toys similar to those previously recalled for Dutch shoppers but still on sale in Britain. Five were found to contain asbestos fibres, according to scientists at Brunel University’s experimental techniques centre.

“Although the risk to health is small because the quantities of asbestos are small, there is still a risk,” said Brunel’s lead scientific officer, Ashley Howkins. “The younger the child exposed the more chance they have of developing symptoms.”

The five products affected were: Fun Sand, Sand Art Bottle manufactured by the HTI Group and sold by the toy website Curious Minds; Glitter & Glow, Magical Sand Art by KandyToys available on Glowtopia; and three products bought from Amazon – Sand Filled Weirdo, Wordpad Montessori Sand Tray and 4 Pack Stretchy Gorilla Toy.

Amazon has since removed the Weirdo and sand tray from sale and said it was investigating the gorillas. A spokesperson said: “When we identified safety concerns related to sand-based toys, we proactively removed affected products – including play sand and kits – from our European stores, and now require a test from an accredited lab prior to listing.”

Curious Minds issued a recall notice and refunds to customers within an hour of being notified by the Guardian. Glowtopia said it would remove the sand art from its website and contact affected customers while awaiting guidance from the KandyToys on whether a recall would be issued. HTI and KandyToys were contacted for a comment.

Customers are advised to pack the contaminated products in sealed double bags and seek council advice on disposing of them.

The latest recalls lay bare the disjointed nature of safety regulation in post-Brexit Europe. Toys recalled in some EU countries after asbestos traces were discovered remain for sale in others, such as the UK. The European Commission’s centralised product safety website Safety Gate publishes only a partial list of products recalled by different member states.

Richard Clevers, an investigative journalist on the Dutch news platform Algemeen Dagblad, said: “Product warnings are piling up but differ from country to country and the European system intended to provide an overview is failing consumers.

“Anyone wanting to know which toys are affected must monitor the websites of different regulators across the continent.”

Retailers have criticised the UK’s product safety policy, which relies on manufacturers and importers to ensure that products are safe. Post-Brexit health and safety laws have removed powers to ban products thought to pose a health hazard without waiting for scientific evidence. Instead, the onus is on exporters, importers and retailers to test goods and inform regulators if asbestos is found.

Wendy Hamilton, the owner of Curious Minds, said: “There is no requirement for independent verification before products reach the market.

“It’s concerning that no alert was issued to UK retailers when similar products were recalled in the Netherlands. While importers and distributors have a legal duty to notify authorities when they become aware of an unsafe product, there is currently no clear requirement for them to notify retailers.

“As a small independent retailer we only found out because you contacted us.”

The UK minister for product safety, Kate Dearden, said: “It is deeply concerning toys are being sold with asbestos, and I know this is worrying for parents. We are continuing to further investigate how products containing this have entered the UK market.

“We have introduced new powers to ensure product safety is as robust as possible and are consulting on how to strengthen our work on tackling unsafe products online.

“Businesses must ensure they are selling safe products and act when they have failed to do so. We will continue to work closely with the EU and ensure any toys sold in the UK which test positive for asbestos are removed from sale and recalled.”

The European Commission was contacted for comment.