Tests were carried out in Germany, Hungary, the Netherlands, Slovenia and Slovakia on nearly 200 sets of light strings in all price categories.

The samples were checked against over 20 requirements, and many failed more than one test.

The commission found thin wiring, weak cord anchorage and poor insulation in many strings of lights. Just over 40% of the samples were made in China.

In Hungary, nearly 96% of the lights were found to be hazardous. In the Netherlands, 56% failed to comply with EU safety standards. Although only five countries took part in the survey, it is likely the same lights are being sold across the EU.

Consumer commissioner Meglena Kuneva said the findings were a wake-up call.

She urged EU member countries to do a better job of enforcing safety standards and said industry – manufacturers, retailers, distributors and importers – should also step up their checks. As for consumers, she stressed vigilance, offering the following advice:

buy Christmas lights from reputable dealers never leave Christmas lights on when you are out of the house or in bed if you suspect a problem with your lights, stop using them and return them to the shop.