AMNESTY International has called for the immediate release of Catalan independence figures Jordi Sànchez and Jordi Cuixart, saying their conviction for sedition violated their rights to freedom of expression and peaceful assembly.

The call followed the human rights group’s analysis of the judgment handed down by Spain’s Supreme Court that saw nine pro-independence leaders, including the two Jordis, jailed almost 100 years. Amnesty said the sentences resulted from the “vague definition” of the crime of sedition in Spain’s criminal code, and “an overly broad and dangerous interpretation of this definition by the Supreme Court”.

Daniel Joloy, a senior policy adviser with Amnesty, said: “Jordi Sànchez and Jordi Cuixart must be released immediately and their convictions on the charge of sedition must be quashed. Whilst our analysis did not find any factors suggesting that the trial as a whole was unfair, it is clear that the Supreme Court’s interpretation of the crime of sedition was overly broad and resulted in criminalising legitimate acts of protest.”

Sànchez was president of the Catalan National Assembly (ANC) while Cuixart led Omnium Cultural. Amnesty’s co-ordinator in Catalonia, Adriana Ribas, defended their right to promote peaceful protests: “As individuals at the time, Jordi Sànchez and Jordi Cuixart had the right to express their opinions, contrary to the decision of the Constitutional Court that prohibited the holding of the referendum and also had the right to organise peaceful meetings to support independence or the celebration of October 1.

“Although the purpose of any of these meetings was to try to prevent a lawful police operation, as stated in the sentence, in what Jordi Sànchez and Jordi Cuixart did there was no direct incitement to violence.

“Amnesty International considers that the Supreme Court has not shown that imposing such a severe sentence ... is proportional in relation to the peaceful acts that are attributed to them.

“Everyone has the right to know if their conduct may constitute a crime.

“But this ruling demonstrates that the vague nature of the definition of the crime of sedition allows it to be used excessively.

“The interpretation of this crime by the Supreme Court could have a chilling effect that could prevent people from participating in peaceful protests without fear.”

The two Jordis organised peaceful, but sizeable, protests as officers from Spain’s National Police raided Catalan government offices searching for material relating to the 2017 referendum.

They were each jailed for nine years after spending two years in “preventative detention”.

Amnesty Spain’s director, Esteban Beltran, said: “The sentences given to Jordi Sànchez and Jordi Cuixart clearly constitute an excessive and disproportionate restriction on their rights to freedom of expression and peaceful assembly.

Parliament must urgently revise the definition of the crime of sedition to avoid criminalising peaceful acts of civil disobedience or unduly restricting freedom of peaceful assembly or expression.”