MOSCOW. Dec 26 (Interfax) - The head of Russia's oldest independent human rights group has warned that the Sakharov Center, a Moscow-based nongovernmental human rights organization named after famous Soviet physicist and dissident Andrei Sakharov, may close itself down now that Russia's Justice Ministry has formally categorized it as a "foreign agent."

"Moscow must not be deprived of the Sakharov Center, which is a living memory of a great scientist and thinker whom our people have given the world in the 20th century. But to demand that the Sakharov Center tag itself as a foreign agent means to shut it," Moscow Helsinki Group leader Lyudmila Alexeyeva said in a letter to the Russian leadership.

"The center will be closed down in order to evade Andrei Dmitriyevich's name being dishonored. To shut the Sakharov Center in the city where Sakharov was born and lived, where he is buried and where there is an avenue named after him is the same kind of barbarity as to demolish the monument to [Russian 19th-century poet Alexander] Pushkin on Pushkin Square or to close down the world-famous Moscow Conservatory," Alexeyeva said.

On Thursday, the Justice Ministry announced that several nonprofit organizations, including the Sakharov Center, had been added to the list of "foreign agents."

Another rights group, Memorial, also protested the Justice Ministry's decision.

"We demand an immediate end to the campaign of hanging tags on independent organizations. This campaign replicates some of the worst instances of harassment of dissidents in the Soviet years," Memorial leader Arseny Roginsky told Interfax.

"Declaring the Sakharov Center a foreign agent is not only a deliberate insult to this center but also an insult to the memory of Andrei Dmitriyevich Sakharov, which takes us back to the era when he was himself incessantly accused of betraying his country and serving the interests of the West," Roginsky said in a statement released in Moscow on Friday.

The Sakharov Center, which is an international entity, was up in Moscow in 1990 by Sakharov's family and friends of the dissident, who is, among other things, known as the creator of the Soviet hydrogen bomb. It is mainly involved in research, including studies of Soviet-era persecutions.

"The dates are also important: the 'snap inspection' that underlay the decision of the Justice Ministry began on December 13, the eve of the 25th anniversary of Andrei Dmitriyevich's death," another senior figure at Memorial, Alexander Cherkasov, told Interfax on Friday.

"It's also important what the Justice Ministry considered to be 'political activities' - the grievances were with the content of free debates that the Sakharov Center had been organizing. Andrei Dmitriyevich, in his famous 'Deliberations