MOSCOW - Defenders of Memorial, Russia's most prominent rights group, urged the Supreme Court on Thursday to dismiss a case to shut it down, saying the move would mark a dark day for the country.

In court for alleged violations of its designation as a 'foreign agent,' Memorial is facing its biggest threat since being founded by Soviet dissidents including Nobel Peace Prize laureate Andrei Sakharov in 1989.

A pillar of Russian civil society, Memorial has built up a huge archive of Soviet-era crimes and campaigned tirelessly for human rights in Russia.

Prosecutors have asked the Supreme Court to dissolve Memorial International, the group's central structure, for alleged failures to use a 'foreign agent' label as required under a controversial law regulating groups that receive funding from abroad.

The move has sparked widespread outrage, with supporters saying the shuttering of Memorial would signal the end of an era in Russia's post-Soviet democratization.

It comes in a year that has seen an unprecedented crackdown on opponents of President Vladimir Putin, including the jailing of top Kremlin critic Alexey Navalny and the banning of his organizations.

During the hearing, which lasted for several hours before being adjourned until December 14, prosecutors accused Memorial of 'systematically' failing to use the foreign agent label and of trying to hide its status.

One asked Memorial co-founder Yelena Zhemkova at what point she had started putting the label on her business cards.

People gather outside Russia's Supreme Court ahead of consideration of a prosecutor's request to dissolve Memorial International, a human rights group, for allegedly violating a controversial law on 'foreign agents,' in Moscow, Nov. 25, 2021.

'Insult to millions'

Memorial's lawyers and founders denied any serious violations, saying its material was properly marked and that only an insignificant number of documents may have been missing the label.

They emerged from the hearing to applause from supporters.

'We will continue to fight to prove that an organization that has worked for 30 years to help people cannot be closed because of unfounded technicalities,' Zhemkova said.

More than 200 people gathered outside the court on a cold Moscow day to support the group, some wearing black face masks reading 'Memorial Cannot Be Banned.'

Maria Krechetova, 48, a philosophy teacher, said shutting Memorial would be an 'insult to the millions' of those who suffered under the repressive Soviet regime.

'Banning Memorial would deal a final blow to the idea that a person means something [in Russia], and that their rights mean something,' she said.

'Memorial plays a huge role in our country. This organization, above all, studies history, repressions,' said Arina Vakhrushkina, 18. 'It is a page in our history the authorities are trying to turn and forget about. They only want to be proud of our victories.'

More than 100,000 people have signed an online petition asking for the case to be dropped.

Thursday's hearing was in one of two cases brought this month against the group and is being heard by the Supreme Court because Memorial International is registered as an international body. The ruling will not be open to appeal in a Russian court.

The other case, against the Memorial Human Rights Centre, began in a Moscow court on Tuesday and will continue later this month.