Russian science fiction writer Dmitry Glukhovsky, the author of the popular "Metro 2033" novel, set in the ruins of the Moscow metro system following a nuclear war, who has been in the crosshairs of the authorities for months, insists he will not stop speaking out against Moscow, despite facing years in jail after being charged over criticism of the war in Ukraine.

Even in the center of the European Union, where he was attending the Frankfurt Book Fair, Glukhovsky admitted that he did not feel safe.

But the 43-year-old – who says he lives in Europe, but declines to specify where – told Agence France-Presse (AFP) that he will continue to voice criticism when he deems it necessary.

"When something outrageous has happened in Russia, I have to comment on it," said the author, who had security guards accompanying him at some of his talks at the fair.

Glukhovsky, who has spoken out against Moscow's invasion in social media posts and opinion pieces for Western media, said the way he was being targeted would have been "unthinkable" a few years ago.

"The regime is transforming itself into a real dictatorship. Even one voice against (it) is already a danger," he said.

"When the regime was authoritarian, it was way more flexible."

'Absurd, grotesque'

Glukhovsky has been caught in a widening crackdown against dissent, launched in the wake of Russia's invasion of Ukraine.

Authorities have introduced a law that imposes hefty jail terms for publishing information about the military which are deemed false by the government.

In June, a Russian court ordered his arrest in absentia. He says that he has been accused of discrediting the Russian military, and acting out of political hatred towards Russian President Vladimir Putin.

The author and former journalist says he now faces up to 15 years in jail if he returns home and is convicted, as well as a hefty fine.

Earlier this month – after he criticized Russia's partial mobilization to support the faltering efforts of its military – Moscow labeled the author a "foreign agent."

The term, reminiscent of the "enemy of the people" of the Soviet era, has been used extensively against opponents, journalists and human rights activists accused of conducting foreign-funded political activities.

"Reality is turning absurd and grotesque way faster than we could have imagined," said Glukhovsky at the annual book fair, the world's biggest publishing event, which wrapped up at the weekend.

Rather than a "foreign agent," the writer sees himself as a "patriot."

Glukhovsky said he just wants Russia to "become a normal European country, leave its old imperial ambitions behind, and modernize, (to) just stop oppressing its own people and causing trouble to the neighbors."

"That, I think, is the most patriotic thing that you can come up with," he added.

'Based on lies'

As for the recent legal moves, Glukhovsky concedes they have made him more "watchful" for potential threats, even when outside Russia.

"You can't really feel safe," he said, pointing to the poisoning in Britain of dissident Alexander Litvinenko which London blames on Moscow.

"The rules that were applicable up until now, are not applicable any longer."

The author sees no prospect of returning to Moscow in the near future, fearing he will be arrested as soon as he arrives.

And even if he does go back, Glukhovsky believes a great deal will have changed as Russia undergoes a radical transformation.

"I will not find the country I love," he said.

And while Putin's hold on power appears unassailable, Glukhovsky says it will not go on forever – and urges people to hang on "until this rotten, fake dictatorship crumbles."

"And it will crumble, inevitably," he said. "Because it's based on lies."