Christmas lights bought from online marketplaces are being sold illegally and in some cases putting users at risk of electric shocks or fires, a consumer group has found.

Which? tested Christmas tree lights at the cheaper end of the price range – all £15 or under – bought from online marketplaces AliExpress, Amazon, eBay and Wish, and found that 10 of the 12 sets of lights bought failed to meet the requirements of the Electrical Equipment (Safety) regulations and could not legally be sold in the UK.

Amid the cost of living crisis, there are concerns more people could turn to cheaper lights in a bid to save money – but it comes with risk.

These latest findings further support Which?’s calls for online marketplaces to be given greater legal responsibility to prevent dangerous and illegal products being sold on their sites.

One set of lights bought from a seller on Wish was so badly made that it posed both an electric shock risk to anyone using it and was also a fire hazard. The Fairy LED string lights, costing £13, had problems with the cable, the control box and the plug.

The build quality was so poor that the white control box could easily be pulled apart by a child, exposing accessible live parts. Wires could be pulled out by hand with little force.

The product was also marked as being waterproof, but Which? found no evidence of this when it took it to pieces and examined the components.

Another set of lights bought from a seller on AliExpress for £13.23 were so poorly manufactured that they could give anyone using them an electric shock.

Which? found poor-quality soldering and a transformer that did not meet the minimum requirements for creepage and clearance distances, which is the space between the live and neutral sections of the circuit board. This means the lights present an electric shock hazard for users.

The pins on the plug were too short and there were numerous problems with the packaging, markings and documents provided. Finally, during Which?’s electrical strength test, the lights blew. These lights are illegal to sell in the UK and dangerous.

All four sites said they have removed the products found to be illegal and for sale from their platforms.

In a statement, Wish said: “Product safety is a top priority for Wish, and we have clear policies in place that prohibit the listing or sale of items on our platform that violate local or other applicable laws, regulations, and/or safety standards.

“As soon as we were made aware of these unsafe items being listed on our platform, we took immediate steps to take them down and conduct monitoring over certain other identical merchant listings.”

Out of the 12 sets of lights, just two – one from Amazon and one from eBay – passed all of the tests by Which? and were legal to be sold and safe to use.

Both sites said they took safety “very seriously”.

An Amazon spokesperson said: “We have proactive measures in place to prevent non-compliant items from being listed and we continuously monitor our store so customers can shop with confidence.”

Ebay added: “Our close working relationships with stakeholders and regulators are an important part of our global product safety strategy for keeping our platform safe. Our Regulatory Portal enables authorities from around the world to report listings of unsafe products for swift removal.”

Sue Davies, Which? Head of Consumer Protection Policy, said: “Cheap Christmas lights could be tempting for many of us trying to save money amid the cost of living crisis – but our latest research shows consumers could be putting themselves in danger due to online marketplaces failing to take safety seriously.

“The government must make online marketplaces legally responsible for dangerous and illegal products sold through their sites so that people are better protected.”