A Paris court has ordered Twitter to reveal the names of France-based users who have posted anti-Semitic messages.
Following complaints linked with several racist tweets, the Paris High Court told Twitter to reveal certain data to France's Union of Jewish Students (UEJF), along with four other bodies, if requested.
The site later blocked the posts, but appealed against the decision to hand over user IDs.
"We are disappointed that the court has decided not to hear our appeal. We are considering our options, including resubmitting the appeal," said a Twitter spokeswoman.
However, Twitter had apparently not managed to present convincing enough evidence for withholding users' identities, with a Paris appeals court ruling that it had failed to provide an "easily accessible and visible" way for people to notify the site's management team of undesirable content.
The case has resulted from the UEJF arguing that tweets containing the hashtag #unbonjuif (#agoodjew) violated French law banning incitement to racial hatred. The group asked Twitter to remove the posts.
The company fulfilled the request, making the posts invisible to French users and pointing out to the BBC that the site did not monitor content, but reviewed reports about messages that might be illegal.
In order for authorities to request personal details of an individual on Twitter, the demand has to undergo a process called MLAT (a mutual legal assistance treaty) - in place between France and the US.
However, UEJF and four other human rights groups have ignored this process, pushing for Twitter to reveal user data with disregard for MLAT.
Twitter filed its appeal in March after the UEJF argued that Twitter had not respected the time frame of 15 days in which to reveal the user ID requested.
UEJF president Jonathan Hayoun has said: "Twitter has not made any progress in regards to respecting our country's laws. The first step towards making any kind of progress could be finally listening to the court's decision, and making sure that its social network is not a lawless place."