The man who oversaw Nestlé's Nespresso brand of coffee machines has sued his former employer for alleged patent infringement.

Ethical Coffee Company, which makes coffee capsules that can be used in the Nespresso machine, has claimed that a change to the way Nestlé manufactures the device infringes its patent.

In a lawsuit filed at a Paris court, Ethical Coffee, which is fronted by Jean-Paul Gaillard after he left Nespresso in 1997, said it has suffered at least €150 million ($174 million) in losses since the change was introduced in 2010.

The patent at issue is European number EP 2312978 B1, called "Device for preparing a drink extracted from a capsule".

Ethical Coffee has said the device now used by Nestlé prevents competitors' products from working in the machine.

In its complaint, filed at the Tribunal de Grande Instance (Grand Instance Court) in Paris on Tuesday (January 20), the company said that Nestlé introduced a "harpoon" mechanism in 2010 that stopped rival capsules, including Ethical Coffee's, from working properly in Nespresso machines.

Neither Nestlé nor Ethical Coffee responded immediately to a request for comment.

But, a Nestlé spokesman told the Agence France-Presse news agency that it denied any claims of patent infringement and said it would fight the case in court.

Gaillard was chief executive of the Nespresso unit from 1988 to 1997.

In a statement to news website Beverage Daily, Ethical Coffee said it has not ruled out further litigation in other countries where it believes its patent is being infringed.

Nestlé is no stranger to controversy surrounding its Nespresso machine.

In October 2013, WIPR reported that a patent covering the machine had been revoked by the European Patent Office.

Just a few months before that decision, the English High Court ruled that manufacturer Dualit, which sells coffee pods compatible with Nespresso machines, was not infringing Nestlé-owned patents. (Source: WIPR)