"This is a purely political and unfriendly act," he said. "I don't get why they would sacrifice U.S.-Russia relations in order to reap some political dividends at home."

The Senate last week adopted legislation requiring the United States to deny visas and freeze assets of people involved in the prison death of Russian anti-graft lawyer Sergei Magnitsky and other alleged rights violators.

President Barack Obama is expected to sign it into law soon.

Putin warned the Magnitsky Act would further strain a relationship tested by the conflict in Syria and the treatment of critics of the Kremlin since his return to the presidency in May.

"Why do they need this? They talk about a 'reset' when they themselves make the situation worse," Putin said, referring to Obama's efforts in his first term to improve relations.

TIT FOR TAT

He voiced support for a retaliatory bill to be debated on Friday in Russia's lower house, the State Duma. It would bar entry to Americans deemed to have violated the rights of Russian citizens abroad.

"I think this is absolutely right that the State Duma rolled out this initiative," he said. "We need to make sure though that the decisions we take are adequate and not excessive."

Russia has said it could take unspecified measures in addition to the bill, but denies any connection between the Magnitsky Act and its announcement on Friday of restrictions on meat imports from several countries including the United States.

Pro-Kremlin deputies said the bill, to be debated in the first of three readings on Friday, may be named after Dima Yakovlev, an 18-month Russian infant who died after his adoptive U.S. family left him locked in a vehicle in Virginia in 2008.

Putin criticised U.S. authorities for their handling of cases involving violence against adopted Russian children.

He also pointed to secret CIA jails abroad and treatment of inmates in the Guantanamo Bay facility in Cuba, saying Washington had no right to take the moral high ground.

"For eight years now they have failed to shut down Guantanamo, [where] they extrajudicially hold people in irons, like in the Middle Ages," he said.

"United States set up secret prisons, legalised torture during investigation. And these people are pointing at our faults!"