CyberJunta, a group of Ukrainian hackers with ties to the country’s SBU secret service, has leaked thousands of confidential emails allegedly coming from the email account of Vladislav Surkov, a key advisor to Russian President Vladimir Putin on Ukraine, detailing Kremlin subversion plans there and in other parts of the former Soviet Union.

The emails support claims that Moscow exerts continual and extensive influence over pro-Russian breakaway regions in Ukraine, Moldova and Georgia, despite the Kremlin’s rejection of the correspondence as fake.

According to the leaked messages, Kremlin officials approved government appointments, laws and press statements for Georgia’s breakaway regions of South Ossetia and Abkhazia, Moldova’s Transnistria and the rebel-held Donetsk and Luhansk regions of East Ukraine.

“This is the clearest yet indication of high-level Russian involvement in the organisation of the separatist republics,” Anders Fogh Rasmussen, former Nato secretary-general, was quoted by the Times newspaper as saying. “It demonstrates Russia’s subversive tactics, which is why I’m calling for sanctions against Russia to have a 12-month renewal.”

The Russian leadership strenuously denies providing military support to pro-Moscow rebels in East Ukraine, despite the capture of numerous armed Russian servicemen there. But the emails fill out the picture of an entire network of coordination from Moscow, including in the management of the rebel-held areas, from the early days of the conflict that quickly engulfed the Donbas region in 2014.

One email dated from May that year, weeks after a pro-Russian insurgency broke out in the region, received by Surkov and quoted by the British newspaper, lists prospective ministers for the rebel government for the Kremlin’s approval.

Another message, sent in June 2014 to Surkov by rebel leader Denis Pushilin contains budget calculations for a press office and newspaper and suggests that the project was funded directly by Putin’s office, the Times reported.

The Kremlin said the emails were fabricated, with Interfax quoting Putin’s spokesman Dmitry Peskov as saying that Surkov doesn’t use email at all.

Meanwhile, Russian entrepreneur Yevgeny Chichvarkin, who currently lives in exile in London, confirmed the authenticity of his email exchange with Surkov in 2013-2014, which was among the leaked emails, in a post on his Facebook account.