Russia's top opposition television channel vowed Tuesday to fight attempts to silence it after several providers took it off air under apparent pressure from authorities.Dozhd (TV Rain), an independent Internet and cable channel known for its critical coverage of President Vladimir Putin, pledged to do all it could to avoid closure, and offered cable operators free content until the year's end."Our independence irritated them," general director Natalia Sindeyeva told a news conference, in an apparent reference to the authorities."I will fight until the end so that the independent channel can continue its work."All Russia's major television channels are state-controlled.In recent days several providers have dropped Dozhd from their television packages in what the station, which depends on advertising revenue, called a campaign of intimidation.On Monday major satellite provider Tricolor TV said it would drop the channel from February 10, a move the station called "a red line"."The operators made the decision not of their own free will but under pressure," said Dozhd co-owner Alexander Vinokurov.The station's management however stopped short of directly blaming the Kremlin for its troubles.The pressure on Dozhd began late last month after it announced a phone-in poll asking whether Leningrad should have been surrendered during World War II in order to save hundreds of thousands of lives during the siege by Nazi forces.Senior lawmakers called the poll unpatriotic and called on prosecutors to probe the station over possible extremism.Dozhd swiftly apologised and pulled the poll, but Putin's spokesman Dmitry Peskov told the station it had "crossed all the limits of what can be tolerated."Dozhd management said the poll was a pretext for a crackdown. They linked the pressure to a report on an investigation by top opposition leader Alexei Navalny into luxury homes owned by ruling party bosses.Dozhd supporters and political commentators said the channel was being punished for its independence.Several members of the president's human rights council said on Tuesday they were "deeply outraged" by the provider's decision to drop Dozhd and urged interior minister to investigate."They are too brave, too honest," Irina Lesnevskaya, publisher of opposition magazine The New Times, said of the channel.Navalny said the TV providers were implementing "an illegal order to introduce censorship.""I know a huge amount of people who hooked up to cable television only to watch Dozhd," he wrote on his blog."Not because they are major dissenters but because it's impossible to watch news on other channels."