A Russian protester who faces up to five years in prison for throwing a plastic bottle at police said Thursday he fled the country amid an unrelenting crackdown on the opposition.

Aidar Gubaidulin, a 26-year-old programmer, was among more than a dozen people who were arrested following anti-government protests demanding fair elections this summer.

He fled the country this week after realising he could soon be given a lengthy jail term, his lawyer Maxim Pashkov told AFP.

“This decision did not come easy to me but the events of the last few days left me no choice,” Gubaidulin said on Facebook.

“I've left the country and will not return anytime soon.” Gubaidulin, who tossed an empty plastic bottle towards police at a July rally but did not hit anyone, was arrested and charged with mass unrest.

He was later released from pre-trial detention and eventually charged with threatening to use violence against police.

Pashkov said Gubaidulin decided to leave Russia after a court on Monday upheld the conviction of another demonstrator, Konstantin Kotov, who had been jailed for four years over peaceful protests.

“This affected him very much,” Pashkov said.

Apart from Kotov, five other people received jail terms of between two and five years over the anti-government protests this summer.

Under pressure from supporters the authorities made a few concessions, including releasing from prison actor Pavel Ustinov after he was jailed for three-and-a-half years and giving him a suspended sentence instead.

But as the wave of protests for the most part died down, the authorities once again began to tighten the screws.

This week, the Investigative Committee announced five more detentions of protesters. The latest detentions brought the number of people awaiting trial in jail to seven.

Tens of thousands of people rallied in Moscow this summer after authorities refused to allow allies of opposition leader Alexei Navalny to stand for city parliament in September elections.

Scores of political activists and Kremlin critics have fled Russia in recent years amid an increasing crackdown on dissent.