TOKYO (AP) – Japan has instructed the maker of Crocs to alter the design of the footwear after complaints that children wearing the colourful plastic clogs have had their feet injured on escalators.

The Trade Ministry said last week it issued the warning after receiving 65 complaints about Crocs getting stuck in escalators between June and November last year. Most of the cases involved small children.

Similar complaints have come from the United States as well, where Crocs is headquartered in Niwot, about 30 miles north of Denver. The Washington Metro – one of the nation's largest transit systems – has even posted ads warning about such shoes on its moving stairways. The ads feature a photo of a crocodile, which is the company logo, though the signs don't mention Crocs by name.

There are reports from Singapore to Virginia of instances in which children have had toe nails, and even toes, torn off while wearing Crocs-style shoes on elevators.

In Singapore, a two-year-old girl wearing rubber clogs – it's unclear what brand – had her big toe completely ripped off in an escalator accident last year, according to local media reports.

And at the Atlanta airport, a three-year-old boy wearing Crocs suffered a deep gash across the top of his toes in June.

That was one of at least seven shoe entrapments at the airport last year, and all but two of them involved Crocs, airport officials said in September.

Recent tests by the National Institute of Technology and Evaluation confirmed the spongy footwear can easily get stuck in escalators because of its flexibility and grip, Japan's Trade Ministry said. The ministry also urged supermarkets, railway stations and other commercial facilities to upgrade signs to urge escalator riders to use caution.

The Japanese unit of Crocs has published a statement on its official website warning customers to use caution when riding escalators.

Crocs Inc. in Colorado was reviewing the report from Japan. About 3.9 million pairs of Crocs footwear were sold in Japan last year, the ministry said.