KIEV, Nov. 4 – A Ukrainian hacker group has stepped up its attacks on Russia and claims to have gained access to ‘tons of stuff’ at the administration of Russian President Vladimir Putin.

The revelation, disclosed by the group in an interview with Forbes, comes days after the same group has hacked and released emails allegedly linked to Vladislav Surkov, a top Putin aide.

“We have other interesting stuff from the president’s administration of Russia, tons of stuff,” an anonymous hacker from RUH8 told Forbes. The information allegedly includes emails from Putin’s spokesman, Dmitry Peskov.

RUH8 is part of the Cyber Alliance, which also includes other Ukrainian hacker groups, such as CyberHunta, Falcons Flame and Trinity.

The Ukrainian attack comes as U.S. hackers have already gained access to critical telecommunication and propaganda infrastructure in Russia, apparently preparing to unleash a major attack if Russian hackers try to disrupt the U.S. presidential election on Tuesday.

A report from NBC on Friday cited senior U.S. intelligence officials, who indicated America’s cyber specialists have already compromised Russia’s critical infrastructure, including its electric grid and telecoms networks, in preparation for any necessary retaliation to the targeting of the election.

Fears that Russia will interfere with the election were stoked by a hacker going by the name of Guccifer 2.0, believed to be a front for the cyber force of Russian intelligence agencies, who on Friday encouraged others to target the U.S. vote.

“I’ll be an independent observer at the US election 2016,” Guccifer 2.0 tweeted. “I call on other hackers to monitor the election from inside the system.”

Surkov, one of the architects of Russia's current political system. He is also a key Kremlin figure in Moscow's intervention in Ukraine.

The released emails support the notion that Russia controls the separatist authorities in eastern Ukraine, who have been fighting a war with Kiev since the spring of 2014.

Moscow has consistently distanced itself from the separatist militias, describing the conflict as a "civil war."

There are documents which, it is claimed, are budgets for the breakaway pro-Russian "republics" in eastern Ukraine. There is an alleged plan for Moscow to provide fuel to the separatist-held regions to deal with shortages.

Taken with previous evidence that the Russian military has been involved in the war in eastern Ukraine and supplied weapons to the separatists, Moscow's actions in Ukraine are, according to Eliot Higgins, a British journalist and founder of the website Bellingcat, "at this point completely undeniable.” (nr/fb/ez)