The case was brought to the Strasbourg court by the website Index.hu, a Hungarian national news and information site.

The news portal, along with an association for Hungarian internet firms, had been successfully sued by an un-named real estate company in the local courts.

Hungarian judges found that Index.hu had broken the law by allowing a series of offensive comments to be published below a story about the property firm.

The story alleged that the firm was involved in the charging of unfair fees for property listings online.

Among the controversial comments made was: "People like this should go and s**t a hedgehog and spend all their money on their mothers' tombs until they drop dead."

Index.hu said it had immediately removed the offending comments but could not be held liable for everything readers posted.

The European Court of Human Rights agreed, ruling that the Hungarian court had not balanced the competing rights involved, between the applicant's right to freedom of expression and the real estate website's right to respect for its commercial reputation.

The court criticized Hungarian authorities for accepting at face value that the comments had been unlawful, without examining the conduct of either party or accepting that the news portal had implemented an effective moderation system, and that the comments were taken down.

"Although offensive and vulgar, the incriminated comments did not constitute clearly unlawful speech; and they certainly did not amount to hate speech or incitement to violence," the judges wrote.

Tuesday's ruling will mean that European news sites will no longer be responsible for offensive but lawful remarks made by readers, as long as they have an effective moderation system in place, and any errant comments are removed when requested by a court, according to Tuesday's ECHR news release.

Hungary is regularly criticized by rights groups for its treatment of the media, with Prime Minister Viktor Orban accused of muzzling the press.

Orban brought in new media laws and a powerful central regulator in 2011, followed by a new media tax in 2014 that critics said was an attempt to tame the opposition press and push out foreign broadcasters.