A pro-Kremlin group runs a network of internet trolls, seeks to buy flattering coverage of Vladimir Putin and hatches plans to discredit opposition activists and media, according to private emails allegedly hacked by a group calling itself the Russian arm of Anonymous.

The group has uploaded hundreds of emails it says are to, from and between Vasily Yakemenko, the first leader of the youth group Nashi – now head of the Kremlin's Federal Youth Agency – its spokeswoman, Kristina Potupchik, and other activists. The emails detail payments to journalists and bloggers, the group alleges.

Potupchik declined to confirm or deny the veracity of the emails, but appeared to acknowledge that her email had been hacked. "I will not comment on illegal actions," she told the Guardian.

Nikita Borovikov, the current leader of Nashi, said: "For several years, I've got used to the fact that our email is periodically hacked. When I heard the rumours that it had been hacked, I wasn't shocked, and have paid no attention to this problem. I'm a law-abiding person, and have nothing to fear of hiding, so I pay no attention."

Apparently sent between November 2010 and December 2011, the emails appear to confirm critics' longstanding suspicions that the group uses sinister methods, funded by the Kremlin, to attack perceived enemies and pay for favourable reports while claiming that Putin's popularity is unassailable.

They provide particular insight into the group's strategy to boost pro-Putin coverage on the internet, which in contrast to television is seen as being ruled by the opposition. Several emails sent from activists to Potupchik include price lists for pro-Putin bloggers and commenters, indicating that some are paid as much as 600,000 roubles (£12,694) for leaving hundreds of comments on negative press articles on the internet. One email, sent to Potupchik on 23 June 2011, suggests that the group planned to spend more than R10m to buy a series of articles about its annual Seliger summer camp in two popular Russian tabloids, Moskovsky Komsomolets and Komsomolskaya Pravda, and the daily Nezavisimaya Gazeta. Arkady Khantsevich, deputy editor of Nezavisimaya Gazeta, denied that his journalists accepted money for articles, a widespread practice in post-Soviet Russia.

"Yes, we wrote about Seliger, and will continue to," he said. "But the paper has never entered into a financial contract, including with political parties." He added that the journalist who covered the summer camp had written under a pseudonym, and the newspaper would not be investigating the claim.

A spokesman for Moskovsky Komsomolets's press service declined to comment: "I don't read what they write on the internet about MK being paid for stories about Seliger. It doesn't interest us." Komsomolskaya Pravda has not responded publicly and could not be reached for comment.

The leak comes as Putin faces the greatest challenge to his rule since first coming to power 12 years ago, with mass street demonstrations building momentum before a presidential vote on 4 March that is expected to return him to the presidency after a four-year interlude as prime minister.

Nashi was created precisely to stand up to any such challenge to Putin's rule. It was formed in 2005 after pro-democracy revolutions in neighbouring Ukraine and Georgia. Thousands of Nashi activists, mostly bussed into the Russian capital from neighbouring provinces, took to the streets in December as Russia's protest movement took hold after a contested parliamentary vote.

The Kremlin has been looking beyond the youth movement lately. On Saturday, the day of the latest opposition protest, the Kremlin turned out thousands of people at a rally in support of Putin's candidacy. Despite the fact that Putin remains Russia's most popular politician, reports were widespread that many of those demonstrating in his support had been forced by employers or paid to take part, echoing the picture painted in the emails of a regime determined to keep up the appearance of his popularity.

"These strategies – what they do on the internet and how they gather protests – are very similar," said Alexey Navalny, the anti-corruption blogger who is helping to lead the protest movement. "Their main problem is that they don't have real people who are ready to say something in support of them. They don't have one person who supports them for free. So they pay."

According to the emails, Nashi manipulates YouTube viewcounts and ratings, calling on paid Nashi activists to "dislike" anti-regime videos.

The emails show the particular attention Nashi pays to Navalny, whose anti-corruption blog and Twitter account have been instrumental in organising anti-Putin sentiment. Activists are seen proposing various ideas to Yakemenko – from projects that came to fruition, such as a cartoon video comparing Navalny to Hitler – to others that were rejected, including a suggestion that someone dress up like the blogger to beg for alms in front of the US embassy. Putin and his supporters continue to insist that opposition protests have been funded and provoked by the west.

The correspondence goes some way towards explaining the apparent paranoia, showing how Nashi, curated by Yakemenko and his recently deposed boss, the Kremlin ideologue Vladislav Surkov, spends huge sums of money to create the illusion of Putin's unfailing popularity.

It appears to confirm that a host of pro-Putin stunts advertised as spontaneous acts by average citizens were in fact orchestrated by Nashi. Among these are a web-based group called I Really Do Like Putin and the all-female Putin's Army, which became notorious last summer after hosting a car wash in support of Putin and calling on women around the country to tear their shirts off for the leader.

Speculation that Nashi is behind pro-Putin stunts, pays internet commenters to troll anti-regime sites and orders DDoS (distributed denial of service) attacks have long swirled around. But the emails, if confirmed, would provide an unprecedented look into the system's inner workings.

The Anonymous hackers told the online news portal Gazeta.ru, in an interview published late on Monday that they carried out the hack, planned since spring of last year, "as a sign of protest against the government's actions in the public internet sphere". "Our ultimate goal is to not allow bandits to bring the Russian internet to its knees," the group said.

The Russian government has so far avoided cracking down on internet freedoms, and both Putin and the current president, Dmitry Medvedev, have spoken out against internet censorship. Yet activists have long complained of co-ordinated attacks that have brought down websites or flooded commentary with pro-Putin spam. Several liberal websites, including those of the radio station Ekho Moskvy and the election monitoring group Golos, were brought down by DDoS attacks on the eve of the country's 4 December parliamentary vote.

"Everything that has been published, we already know," Navalny said. "[Nashi] undertake the organisation of provocative actions, both physically and on the internet."

Opposition leaders have also accused Nashi of being behind a series of attacks including repeated scuffles with the liberal youth leader Ilya Yashin and an incident in which ammonia-laced cola was thrown in the face of the former deputy prime minister Boris Nemtsov. Nashi denied being involved in the latter.

As British-Russian relations spiralled towards a low in 2006, the group launched a campaign of harassment against the former UK ambassador Tony Brenton after he met opposition groups. It has since turned its attention to the internet, analysts say.

The emails suggest a palpable concern within Nashi and the Kremlin after Russia's contested parliamentary vote on 4 December launched an unexpected protest movement that brought thousands on to the streets of Moscow for the first time. Activists write to Yakemenko proposing various "provocative actions" designed to discredit the quickly growing movement.

On 11 December, one day after up to 50,000 people gathered on Bolotnaya Square in an unprecedented show of discontent with Putin, Borovikov writes to Yakemenko to propose different means of dealing with the opposition. "If we don't do this all in time, these public opinion leaders will continue to protest on the streets and all this will turn into a Ukrainian Maidan," Borovikov writes, referring to the square in Kiev that hosted Ukraine's pro-democracy, "orange revolution".

Asked by the Guardian about the hack, Borovikov said: "I'm not ready to discuss any provocations. It's not correct to discuss this in principle. Unfortunately, it has become part of life to get into personal things, but it is not very nice to discuss it. It's amoral. To think Nashi, as a social youth organisation, has a lot of money is a delusion. The main resource of any social organisation is its people: people's time, people's efforts."

Yakemenko's office directed all queries to Potupchik, who did not answer subsequent requests for comment.

Revealing rumours long taken as fact, the emails are unlikely to have an effect on the opposition's methods or goals. Borovikov's alleged words may turn out to be prescient. "Either the powers fulfil our legal demands or people will turn out and refuse to leave," Navalny said.

Most of the leaked emails are brief and discuss the practicality of orchestrating the pro-Putin work that Nashi feeds on. One email provides a rare glimpse into a top activist's thinking, as Potupchik emails several Nashi leaders, known, in the group's lingo as commisars, to speak highly of Yakemenko.

"If someone thinks that they can be on my team and not play by my rules, they can leave," Potupchik, well known for her colourful language, allegedly wrote on 26 October 2011.

"If you think that in this country another person can be found who would create such a structure, who would drag into this work all the dregs of the provincial towns, who would make provincial shits into princesses of the capital, then fuck off. Maybe you're not happy with something. Maybe you're not paid that much, you don't like how you're treated, don't like your office, or your work schedule."

"I ask you not to bother me and to leave this horrible work."

• Additional reporting by Ilya Mouzykantskii.