* Russia says legislation will harm relations
* Tough response threatened to bill in Congress
MOSCOW, Nov 15 (Reuters) - Russia warned on Thursday that the U.S. Congress will damage relations with Moscow if it passes legislation designed to punish Russian officials for human rights violations, and threatened a firm response.
U.S. lawmakers may vote on Friday on a measure directing the government to deny visas to Russian officials involved in the detention, abuse or death of Sergei Magnitsky, a lawyer who died in jail in 2009, and freeze any assets they have in U.S. banks.
"Such a step will unavoidably have a negative effect on the whole range of Russian-U.S. relations," Russian Foreign Ministry spokesman Alexander Lukashevich told a news briefing.
"We will certainly not leave the introduction of essentially anti-Russian visa and financial sanctions without consequences," he said. "We will have to react, and react toughly, depending on the final version of this unfriendly provocative act."
Adoption of the bill named after Magnitsky, who has posthumously become a symbol of corruption abuse of Russians who challenge the authorities, could undermine efforts to smooth relations at the start of President Barack Obama's new term.
Russian President Vladimir Putin has welcomed Obama's re-election and said he wants to improve ties and increase trade, but has made clear he will not tolerate criticism from the United States about human rights.