Russian officials are promising a tough response to US legislation that would impose sanctions on Kremlin officials if Congress finds them responsible for violating human rights.
On Friday, Washington passed a bill that established permanent normal trade relations with Russia, repealing a 1974 act which limited trade because of the Soviet Union's treatment of Jews. It had been waived annually since 1989, two years before the Soviet Union collapsed.
But a provision of the legislation named after lawyer also would impose sanctions on officials responsible for human rights violations.
Magnitsky was a lawyer, aged 37, representing a Britain-based capital management company in 2008 when he exposed alleged tax fraud involving Russian police. He claimed the scam had cost Russia about US$200 million.
Magnitsky was arrested on charges of organising tax evasion for his own firm's executives. He was allegedly tortured and died in a Moscow prison in November, 2009.
The circumstances of his death and the fraud claim have never been properly investigated, human rights activists say.
The Russian Foreign Ministry said the legislation could damage relations with the United States.
"The passage of the Magnitsky Act is another attempt of flagrant politicising the issue of human rights," the ministry's envoy on human rights, Konstantin Dolgov, said.