UPDATE 1-Russia investigates TV channel over protest coverage

* Prosecutors investigate independent television channel

* Putin facing major mood change among urban voters

* Journalists fear media crackdown (Recasts, adds comment and details)

By Guy Faulconbridge

MOSCOW, Feb 16 (Reuters) - Russian prosecutors said on Thursday they had opened an investigation into an independent television channel over its coverage of protests against Vladimir Putin's 12-year rule, less than three weeks before a presidential election.

Prime Minister Putin hopes to convincingly win the March 4 election in order to take the sting out of a growing urban protest movement which casts him as an authoritarian leader who rules through a corrupt and tightly controlled political system.

But there have been signs that Putin's patience with independent media is wearing thin and on Thursday Moscow prosecutors said they were investigating the financing of coverage of the opposition protests against him by the Dozhd cable and Internet television channel.

Prosecutors said they had acted after an official request from a lawmaker in Putin's ruling United Russia party.

"Dozhd in my opinion became an information sponsor and part organiser of these events," the 27-year-old lawmaker, Robert Shlegel, said on Twitter. Shlegel is a former spokesman for the Kremlin's pro-Putin youth movement, Nashi.

The television station's general director could not be reached for immediate comment but posted on the Internet a copy of a letter dated Feb. 16 from prosecutors explaining the investigation

Putin, whom Russian journalists say rolled back media freedoms during his 2000-08 presidency, has complained about coverage by independent media outlets, even accusing Russia's most prominent radio station of "pouring shit" over him.

In Russia, where the biggest private television station was raided by armed tax police in masks soon after Putin's March 2000 election win, that sort of language has made some journalists fear a possible crackdown.

The editor of the radio station criticised by Putin, Ekho Moskvy's Alexei Venediktov, accused the authorities of trying to stifle editorial freedom this week when its state-controlled owners demanded changes to the station's board membership.

CRACKDOWN?

But senior Russian journalists said the investigation of the Dozhd television channel was more indicative of a nervousness among Putin's supporters about coverage of Russia's paramount leader rather than the start of a genuine crackdown.

"This shows the nervousness of different state organs and of course could be an attempt by some to ingratiate themselves with their bosses," Stanislav Koucher, a commentator for Kommersant-FM radio station, said by telephone.

"When the authorities want to seriously tighten the screws, it is really very obvious and very visible" he said.

Putin, who was once cast as Russia's "alpha-dog" leader by U.S. diplomats, is scrambling to deal with an unprecedented change in mood among urban Russians, many of whom now openly lampoon him on the Internet through satire.

A turning point in popular perceptions came just two weeks before the disputed December parliamentary election when sports fans booed and whistled the macho former KGB spy as he stepped into the ring at a martial arts fight in Moscow.

One spoof video viewed by more than 3 million people on Youtube has even placed him behind bars.

The mock news report purports to show Putin accused of embezzlement and behind bars in a Russian court room. here

Putin's supporters, who credit Putin with bringing order to Russia after the chaos of the 1990s and presiding over the longest Russian economic boom in a generation, fume at such satire.

They say Putin is still by far the most popular politician in Russia and dismiss the protesters against his rule as mostly naive youngsters who are being manipulated by the West to undermine Russian stability. (Reporting by Guy Faulconbridge, Editing by Timothy Heritage and Andrew Osborn)