About 200,000 fidget spinners have been impounded by customs officials in the Republic of Ireland amid safety fears.
There are concerns over inferior products hitting the market with a surge in demand for the latest must-have toy in recent months.
The spinners, originally designed to help children with conditions like autism deal with stress, have become a playground craze.
There are concerns they pose a choking hazard with their small parts.
In addition to complaints that some are poorly made and break easily, it was recently reported that a 10-year-old girl in the US needed surgery after she swallowed a part of a spinner and it became lodged in her oesophagus.
Some schools have banned the toys because they can distract pupils from doing their work.
The Competition and Consumer Protection Commission (CCPC) said it became concerned that some spinners for sale in Ireland may not meet EU product safety standards.
A spokeswoman said consignments were being referred to their safety unit on a daily basis, so it was difficult to give an exact figure.
"However to date, the CCPC, in collaboration with our colleagues in Revenue and Customs, has suspended the importation of approximately 200,000 fidget spinners," she said.
"We are currently examining samples of those products. If we find that products are incompliant with product safety legislation, the products may be sent back to where they originally came from or destroyed."
Some of those already examined have been declared non-complaint for various reasons, including no visible safety mark, known as the CE marking, or a fake mark.
The CCPC is urging customers to look for a CE mark before they buy, check the box for manufacturer details, use a reputable seller and check if the spinner has any detachable small parts that could lodge in the ears, nose or throat, and cause an injury to a child.