Republican presidential candidate Mitt Romney would support legislation to upgrade U.S. trade relations with Russia only if Congress also passes a measure to go after Russian human rights violators, his campaign said on Thursday, - Reuters reported.

"Gov. Romney believes that permanent normal trade relations (PNTR) should only be granted to Russia on the condition that the Magnitsky human rights bill be passed," Lanhee Chen, policy director for the Romney campaign, said in a statement.

Chen was referring to legislation being considered in Congress that would require the U.S. government to impose sanctions on people believed responsible for the death of Sergei Magnitsky, an anti-corruption lawyer who died in a Russian prison, and other human rights violators.

"(Romney) disagrees with the Obama administration's attempts to scuttle the Magnitsky bill and its overall reluctance to shine a light on human rights abuses in Russia and the Putin government's backsliding on democratic principles," Chen said.

Romney, who faces President Barack Obama in the November 6 election, has taken a tough line on Russia, which he has called the "No. 1 geopolitical foe" of the United States.