The impending trial of a Dutch activist who publicly insulted King Willem-Alexander late last year has sparked outrage in Netherlands and prompted prosecutors to re-evaluate the case based on a century-old law.

Abulkasim al-Jaberi was arrested at a rally in November when television cameras showed him spouting a stream of profanity aimed at the king, Queen Maxima and the royal house.

Prosecutors said the activist would face trial based on a "lese-majeste" (injured monarch) law harking back to 1881, which makes deliberately insulting the king or royal house punishable with a prison sentence of up to five years or a $28,291 fine.

Al-Jaberi was part of a demonstration in Amsterdam against the Dutch "Black Pete" children's figure, the black-faced sidekick that appears at the traditional gift-giving festival of Saint Nicholas, which opponents say is a racist throwback.

Al-Jaberi was handed a $707 fine after his rant, which he refused to pay.

Prosecutors have pulled the summons for Al-Jaberi's appearance in an Amsterdam court on May 27, after Al-Jaberi's lawyer filed an objection amid an public avalanche of outrage, though the charge itself has not been dropped.

Free speech sacred in liberal Netherlands

The charge sparked instant outrage in liberal Netherlands, which sees freedom of speech as a fundamental cornerstone.

Al-Jaberi's words were spray-painted on the Royal Palace in Amsterdam, while protesters took to Twitter with a stream of similar expletives.

"The issue of freedom of expression is sensitive in the Netherlands. It's a very important fundamental right," Stef Ketelaar, a lawyer and historian who studied the lese-majeste laws, said.

The Netherlands' lese-majeste law against insulting King Willem-Alexander and the royal family is rarely enforced. ( Reuters: Jasper Juinen/Pool )

Online, in newspapers and even in parliament many denounced the lese-majeste law as archaic and hardly in tune with modern-day rights.

Amsterdam mayor Eberhard van der Laan said he "laughed" when he heard of the summons and described the law as outdated.

"I know the king a little and I think he sees it more democratically than the law itself does," Mr Van der Laan told Het Parool newspaper.

Prosecution in the Netherlands for insulting the royals is rare and they are often satirised in the media.

The prosecutors said the context in which insults are uttered plays an important role.

"There are cases where freedom of speech prevails, for instance for comedians or those involved in public debate," prosecution spokesman Franklin Wattimena said.

Elsewhere in Europe, lese-majeste laws also apply in Spain, Monaco and Sweden.

Britain also has lese-majeste laws but has not applied them for more than a century, Dutch media reports said.

AFP