The 11 September attacks in New York were an inside job; the South Korean warship torpedoed in March was not sunk by North Korea, but probably by Japan or the US; and the world is run by the secretive Bilderberg Group, who pursue a "New World Order". Not the lonely ravings of a conspiracy-minded blogger, but all opinions aired recently on a satellite channel beamed into millions of American homes.

With its slick graphics, smiling young news-anchors, and round-the-clock coverage, RT is like any other news channel. But there is one major difference, aside from the content: RT, which stands for Russia Today, is paid for by the Kremlin. The channel launched in 2005, broadcasting news mainly about Russia on various satellite packages around the world.

You might remember a provocative ad campaign across London last year, with posters showing pictures of Barack Obama and Mahmoud Ahmadinejad and asking, "Who poses the bigger nuclear threat?"

Download the new Independent Premium app Sharing the full story, not just the headlines

In the US, ads were run on screens inside New York taxis, and the channel even broadcast live on big screens in Times Square. This year, RT went even further in its attempts to infiltrate the US, when a new arm of the channel, RT America, began broadcasting from Washington DC several hours a day, exclusively for a US audience. The focus is not Russia, but America itself, and the radical opinions of some of its guests have been raising eyebrows.

Last month, the Southern Poverty Law Center (SPLC), a well-respected US organisation that tracks hate groups and extremists in the United States, published a report about Russia Today. The group did not label the channel itself extremist, but said it gives undue airtime to conspiracy theorists and extremists. "Its slickly packaged stories suggest that a legitimate debate is under way in the United States about who perpetrated the 11 September terrorist attacks, for instance, and about President Obama's eligibility for high office."

The top brass at the channel, including editor-in-chief Margarita Simonyan, have denied this. "We don't talk about 9/11 any more than US media discusses who was behind the 1999 explosions in Moscow," she told the authors of the SPLC report, referring to the apartment block bombings that were a catalyst for the second Chechen war. "Moreover, our own journalists have never claimed or even as much as hinted that the US government may have been behind the tragedy of 9/11."

This is not strictly true, as the report's authors point out; not only do captions such as "New Yorkers Continue to Fight for 9/11 Truth" appear on screen during stories about the attacks, but on the last anniversary, the channel's website published a four-part series entitled, "911 Reasons why 9/11 was (probably) an inside job". A video of a recent interview with a "9/11 Truther" on Youtube is entitled, "Two planes didn't take twin towers down".

Why does a Russian state channel care about 9/11? The refocusing of the channel away from Russia and towards the US, as well as de- emphasising the connection to Moscow in the channel's name (since last year, anchors and correspondents have been told they must refer to it only as "RT", never "Russia Today") has led some to wonder what the Russians are up to in the US.

There have been suspicions, even among some of those inside the channel, that the aim might be a Kremlin, or even a Russian intelligence plan to stir dissent in the US. At the very least, it seems an attempt by Russia to get its own back on a Western world that often lectures Moscow on democracy and human rights, and shine a light on what it sees as the sore points for the US.

Even before the recent spy scandal about Russian "illegals" in the United States, western intelligence services have been wary about Russia Today's correspondents. One journalist, posted by the Russian channel to a western capital, recalls that she was called to a meeting in a local café by the country's interior ministry before being given her accreditation.

Daily coronavirus briefing No hype, just the advice and analysis you need Enter your email address Continue Continue Please enter an email address Email address is invalid Fill out this field Email address is invalid Email already exists. Log in to update your newsletter preferences Register with your social account or click here to log in I would like to receive morning headlines Monday - Friday plus breaking news alerts by email Update newsletter preferences

"This guy showed up, and he had a dossier with loads of information about me and my past," says the journalist, who does not want her name revealed. "It was pretty obvious he was working in intelligence, and eventually he came out and asked, 'Is Russia Today a front for a spy network?' I thought it was hilarious, but he was serious." One employee of the channel told The Independent, on condition of anonymity: "I have mixed feelings about whether the channel is actually trying to provoke dissent among Americans. That seems the only logical reason to have some of these guests on and to spend so much time talking about these topics. On the other hand, Denis Trunov [the head of RT America] has said multiple times that his only goal is to get YouTube hits and he will have anyone on who will get Youtube hits. He has even suggested having porn stars on to talk about topics like Afghanistan, in the hope of getting hits." Mr Trunov declined to speak to The Independent, but Ms Simonyan, the channel's overall boss, agreed to reply to written questions.

"RT's target viewer is a person capable of critical thinking, one who realises that one or two sources of information are not enough to get a full picture," says Ms Simonyan. "It is someone who wants to know the truth, rather than who passively accepts stereotypes."

Ms Simonyan says RT gives viewers access to "stories they're not going to see on the networks they're used to". Some of the commentators on the channel support this view. Danny Schechter, a veteran journalist and blogger, points to the lack of diversity in the traditional US television networks as one of the main reasons for RT's success.

"The US media today is a very partisan, polarised environment; anyone who brings a perspective that doesn't fit into this partisan fight is considered out of the spectrum," says Mr Schechter, who has recently completed a book calling for criminal prosecutions over subprime loans and the financial crisis. He says that "today's conspiracy theories could be tomorrow's facts", though emphasises that he personally has little time for some of the more extreme views aired on the channel.

But lots of Americans like what they are hearing. Ms Simonyan says independent surveys show that among Washington DC viewers, more than six times as many people choose to tune into RT than to Al Jazeera English – and these are figures for 2009 – before the channel even began its dedicated US-only broadcasts.

"We now have more than 150 million views on YouTube, which is much higher than that of Fox News, CNN, Sky News or Reuters YouTube channels," says Ms Simonyan. "Just a couple of days ago, RT made it into YouTube's All-Time Top 100 Most Viewed Partners list, replacing President Obama's channel." The channel also seems to have ruffled feathers in the traditional media establishment. At one point, RT got into a spat with Fox News host Bill O'Reilly, who rubbished an interview the channel's correspondent Anastasia Churkina had with the radical activist and academic Bill Ayers. "Don't you just want to slap him?" Mr O'Reilly asked viewers of his show, after playing a brief clip of the interview.

"They assigned a Russian interviewer to interview that pinhead who didn't even speak English," crowed Mr O'Reilly, a rather unfair criticism of what was in fact almost flawless English from the Russian interviewer.

In response, RT ran a report turning the heat back on Mr O'Reilly. "The American mainstream media, crusaders of truth, pathological liars, or just scary clowns?" asked the channel's correspondent.

Ms Simonyan claims: "RT is not a state channel. RT is a global news channel, just as Al Jazeera, BBC, France 24 or Deutsche Welle. They may be financed by government, but they are not state channels."

But RT is rather different from the BBC, certainly when it comes to covering the "home" country. Several journalists at the channel have told The Independent that while some coverage of problems in Russia and sensitive issues is allowed, any direct criticism or questioning of Prime Minister Vladimir Putin or President Dmitry Medvedev is strictly prohibited.

With the start of RT America, observers have started to question the coverage of topics other than Russia. Some of the more bizarre moments on RT can sometimes be put down to youthful inexperience (such as the newsreader who clearly skimread the autocue too fast and referred to "North Korean leader King John the Second"), but sometimes it seems something more sinister is at play. One anchor told The Independent that during an interview with a leading scientist working on Aids he was repeatedly pressured by producers to "ask difficult questions" about the "evidence" that HIV doesn't cause Aids at all.

Such strange attachment to any conspiracy theory going has led to some wondering what RT stands for. Others simply see it as inexperience, and welcome a new player in a stagnant media market.

"It's a force for diversity in the media," says Mr Schechter. "They give voice to a lot of people, like myself, who rarely get heard in current mainstream US media. I was part of the start-up team for CNN in 1980, and I see some similarities. It's a channel of young people who are inexperienced, but very enthusiastic about what they are doing."