MOSCOW -- Russian health regulators announced formidable new barriers to the import of meat from the United States late on Friday, in a move some analysts saw as retaliation for American legislation punishing Russian officials linked to human rights violations.
The new Russian regulation requires imported meat to undergo testing for and be certified free of ractopamine, which is added to animal feed in the United States to make meat more lean.
The United States Department of Agriculture considers ractopamine safe and does not test for it. The United States exports about $500 million worth of beef and pork to Russia.
A notice published on the regulator's Web site on Friday said the regulation would go into force immediately, and that during an unspecified "transition period" Russia will conduct its own testing. After the transition period ends, foreign countries will be required to certify their meat exports as ractopamine-free.
The announcement came hours after the Senate passed the so-called Magnitsky Act, which will deny visas and freeze assets of Russian officials who have been linked to the death of Sergei L. Magnitsky. Mr. Magnitsky was detained after accusing Russian officials of embezzlement and died in a Moscow detention center in November 2009.
Gennady Onishchenko, Russia's chief health inspector, responded indignantly to the notion that the ractopamine ban was politically motivated or linked to the Magnitsky Act.
Mr. Onishchenko said there were serious questions about the effects of ractopamine.
"For instance, use of ractopamine is accompanied by a reduction in body mass, suppression of reproductive function, increase of mastitis in dairy herds, which leads to a steep decline in the quality and safety of milk," he told Interfax on Saturday.
The United States Department of Agriculture on Friday asked Russia to suspend the requirement, saying it could effectively halt beef and pork exports to Russia.
American trade and economic officials are expected to travel to Moscow this week to urge the government to postpone the new requirement.
This article originally appeared in The New York Times.