Japan's Trade Ministry is looking into several reports of people damaging toenails on Jibbitz accessories fixed to Crocs sandals in the country.

Crocs Asia warned on its website that children should not wear oversized pairs of the company's distinctive rubber clogs after the incidents, which involved one 19-year-old and two children.

Crocs said that they lost part of a toenail after it became snagged on the clasp of the Jibbitz, a colourful accessory in the form of flowers, butterflies and cartoon animals which fits into the holes of Crocs shoes.

But, the company added, the two children involved were wearing Crocs which were at least 1.5cm larger than their feet, meaning that their toes could come into contact with the Jibbitz.

"Jibbitz attached near the toes could harm toes or toenails," said the company on its Japanese website.

Crocs acquired Jibbitz in 2006 and has developed a 1,600-strong range of designs for the accessories.

The scare in Japan follows reported incidents in Japan and the US of Crocs wearers being involved in entrapment incidents with escalators and moving walkways.

The company maintains that the safe design and maintenance of escalators is the real issue - and has launched a campaign to that effect, alongside warning tags on its footwear.