* Rise in curbs on civil society follow Putin's return - HRW
* Putin started six-year term in May
* Russian Foreign Ministry dismisses report
By Alessandra Prentice
MOSCOW, Jan 31 (Reuters) - Russian authoritarianism rose to levels unprecedented in recent history in 2012, Human Rights Watch said on Thursday, assessing what it called the harshest crackdown on political freedoms in the country since the Soviet era.
Russia introduced restrictive laws, harassed activists and interfered with non-governmental organisations during the year, which saw Vladimir Putin return to the Kremlin and former President Dmitry Medvedev appointed prime minister, the New York-based rights group said.
"Since Putin's return ... not only has the tentative shift towards liberalisation of the Medvedev era been totally reversed, but also authoritarianism in Russia has reached a level unknown in recent history," said Rachel Denber, deputy director of HRW's Europe and Central Asia Division.
Speaking at a news conference in Moscow coinciding with the publication of its annual report on human rights worldwide, Denber also criticised the government's stance toward the West.
Since Putin started a six-year term in May, he has signed laws restricting protests, demanding foreign-funded NGOs register as "foreign agents" and setting new rules on treason that critics say could place almost anyone who associates with foreigners at risk of prosecution.
Several opposition leaders and activists face potential prison terms if convicted on charges Putin's critics say are trumped up, though Putin's spokesman has denied the Kremlin uses courts and police to pressure critics.
"Measures to intimidate critics and restrict Russia's vibrant civil society have reached unprecedented levels," Hugh Williamson, director of HRW's Europe and Central Asia Division, said in a statement.
"Pressure and reprisals against activists and non-governmental organizations need to stop," he said.
"This has been the worst year for human rights in Russia in recent history," he said of 2012. The statement said the Kremlin "unleashed the worst political crackdown" since the breakup of the Soviet Union in 1991.
Russian Foreign Ministry spokesman Alexander Lukashevich said he had not read the report but that Russia would probably comment later and "show that the human rights situation in Russia is not the worst."
He said the Russian ministry's own annual reports have shown that "there are serious systemic problems in the sphere of human rights in the United States and many European Union countries."
"Before you criticise others, you should look at yourself," Lukashevich said at a weekly briefing.