LUXEMBOURG (AFP) - An EU court ruled on Wednesday (March 14) that the design of Crocs shoes cannot be patented in Europe in a blow to the US-based maker of the plastic clogs.

Luxembourg-based judges upheld a 2016 decision by the EU's intellectual property office to cancel the patent because Crocs made the design public before registering it.

Crocs have sold 300 million pairs around the world, according to their manufacturers, attracting devotees because of their comfort and seeming indestructibility, but attracting mockery too for their chunky shape.

"The General Court confirms the cancellation of registration of Crocs' design because it was made available to the public before its registration," said the General Court of the European Union, the bloc's second highest court.

It said Crocs were originally granted a patent in the EU in 2005, but a rival French shoe manufacturer, Gigi Diffusion appealed against the decision in 2013.

The EU patent office agreed, saying that Crocs' design had already been made public in 2003 on its website and at a boat show in Fort Lauderdale, Florida, and therefore "lacked novelty".

Under EU regulations any design which has been made public in the 12 months prior to a patent application cannot be given a patent.