Several top human rights campaigners warned Wednesday of rising xenophobia in Russia, saying politicians were sirring up anti-immigrant sentiments ahead of upcoming Moscow mayoral polls.
Pro-Kremlin and opposition candidates running for Moscow mayor in September 8 elections have all made toughening immigration policies a key plank of their campaigns.
"Our society is being drawn into such depths of visceral hatred that the only way out of it is civil war," said the leaders of five of Russia's top rights groups.
"The current flare-up in the 'fight' against illegal immigration is simply a PR campaign ahead of upcoming elections," they said in an open letter published in Russia's top opposition newspaper, Novaya Gazeta.
"Having put their differences aside, the participants in the pre-election race are unanimously demanding the introduction of visas for the countries of the Commonwealth of the Independent States," they said, referring to post-Soviet countries.
Signatories to the letter included campaigners who are household names in Russia, such as Lyudmila Alekseyeva, head of the Moscow Helsinki Group, and Arseny Roginsky, chair of Memorial.
In recent years, hundreds of thousands of migrants have come to Russia from impoverished, Muslim-majority states of the former Soviet Union such as Tajikistan, often working as street cleaners or on construction sites.
They frequently endure poor labour and living conditions and are increasingly regarded with disdain by many Muscovites.
Russian police routinely raid underground operations in which migrants from southeast or central Asia are exploited by employers, but police themselves are notorious for extorting bribes from such migrants.
Ahead of Moscow's mayoral elections, police have increased their raids and last month arrested 1,200 Vietnamese people living in squalid conditions in a sweatshop.
The capital's pro-Kremlin mayor, Sergei Sobyanin, is seeking re-election.
Anti-Kremlin candidates such as protest leader Alexei Navalny and liberal opposition figure Sergei Mitrokhin have also embraced anti-immigrant rhetoric, accusing the Moscow city administration of hiring migrant workers and essentially becoming the "top slave owner", in Mitrokhin's words.
The rights activists called on Russia's elites to speak out against the growing xenophobia.
"Why are you keeping silent?" they said. "Cannot you, dear scientists and cultural figures, see how the skies over our homeland are getting enveloped by the caustic brown stench?"