Originally posted by the Voice of America. Voice of America content is produced by the Voice of America, a United States federal government-sponsored entity, and is in the public domain. EU, US Demand Release of Kremlin Critic as Calls Grow for 'Magnitsky' Sanctions Henry Ridgwell LONDON - Western leaders have demanded the release of Russian opposition leader Alexei Navalny, who was arrested Sunday on arrival in Moscow after receiving medical treatment in Germany. The 44-year-old Putin critic and leader of the Russia of the Future party was poisoned by a nerve agent in Siberia last August. The Kremlin denies involvement in that attack. "The Russian authorities have arrested the victim of an attempted assassination with a chemical weapon, not the perpetrator," German government spokesperson Steffen Seibert told reporters Monday. "The German government strongly calls on the Russian government to first of all release Mr. Navalny immediately and secondly to fully investigate the circumstances of the chemical weapons attack on Russian soil," he added. Other European leaders echoed that demand, while the United Nations' human rights office said it was "deeply troubled" by Navalny's arrest. U.S. Secretary of State Mike Pompeo used the same words on Twitter: "Deeply troubled by Russia's decision to arrest Aleksey Navalny. Confident political leaders do not fear competing voices, nor see the need to commit violence against or wrongfully detain, political opponents." President-elect Joe Biden's incoming national security adviser Jake Sullivan tweeted: "Mr. Navalny should be immediately released, and the perpetrators of the outrageous attack on his life must be held accountable. The Kremlin's attacks on Mr. Navalny are not just a violation of human rights, but an affront to the Russian people who want their voices heard." Navalny was arrested as he entered passport control in Moscow's Sheremetyevo airport Sunday evening. Dozens of his supporters, who had gathered at a different airport before Navalny's plane was diverted, were also taken into custody. There were further arrests Monday in St. Petersburg as his supporters staged street protests. .