McDonald's has lost its rights to the trademark Big Mac in a European Union case ruling in favor of Ireland-based fast-food chain Supermac's, according to a decision by European regulators.

The judgment, provided to Reuters by Supermac's, revoked McDonald's registration of the trademark, saying that the world's largest fast-food chain had not proven genuine use of it over the five years prior to the case being lodged in 2017.

The Spain-based EU Intellectual Property Office (EUIPO) did not respond to phone calls and emails requesting comment.

McDonald's was not immediately available to comment on the decision, which the company can still appeal.

The ruling allows other companies as well as McDonald's to use the Big Mac name in the EU.

Supermac's said it can now expand in the United Kingdom and Europe. It said it had never had a product called Big Mac but that McDonald's had used the similarity of the two names to block the Irish chain's expansion.

"Supermac's are delighted with their victory in the trademark application and in revoking the Big Mac trademark which had been in existence since 1996," founder Pat McDonagh told Reuters in an email.

"This is a great victory for business in general and stops bigger companies from "trademark bullying" by not allowing them to hoard trademarks without using them."

McDonald's, which sells its flagship Big Mac burgers internationally, submitted printouts of European websites as evidence, as well as posters, packaging, and affidavits from company representatives attesting to Big Mac sales in Europe.

The EUIPO said the affidavits from McDonald's needed to be supported by other types of evidence, and that the websites and other promotional materials did not provide that support.

From the website printouts "it could not be concluded whether, or how, a purchase could be made or an order could be placed," the EUIPO said. "Even if the websites provided such an option, there is no information of a single order being placed."

McDonald's has historically been "extremely litigious" in the area of trademark law and typically does not lose, said Willajeanne McLean, a law professor at the University of Connecticut.

In 1993, McDonald's won a court order blocking a dentist in New York from selling services under the name "McDental."

In 2016, McDonald's defeated an effort by a Singapore company to register 'MACCOFFEE' as an EU trademark.