Two people involved with Kremlin critic Alexei Navalny’s recent political campaign said they have fled Russia due to the massive police crackdown on the opposition linked to him.

Russian regime have in recent months cracked down on groups affiliated with Navalny, who is regarded by many at home and abroad as President Vladimir Putin’s No. 1 foe. He is serving two-and-a-half years in prison for parole violations related to a fraud case he says was politically motivated.

First, a court in June ruled that Navalny’s anti-corruption foundation was extremist. Then, after his allies regrouped around a new network of organisations set up for September’s parliamentary election, authorities started investigating campaign staffers on the same extremism charges.

A number of Mr. Navalny allies have already left Russia.

Ms. Irina Fatyanova, the former Navalny campaign chief in St Petersburg, wrote in her channel on social media on Tuesday that her decision to leave Russia had been spurred by the arrest of fellow campaign manager Ms. Liliya Chanysheva this month.

The case of Liliya Chanysheva has changed a lot and helped me realise I had to leave, she said.

Ms. Chanysheva could face up to 10 years in prison.

Lawyer Mr. Yevgeny Smirnov, who had represented Mr. Navalny’s campaign, told media he had also left Russia “due to constant pressure” which he said included surveillance, although he did not rule out returning to the country.

Mr. Navalny himself has launched his fourth lawsuit attempting to challenge the decision by prison authorities to designate him as a person who follows extremist ideology – which carries additional restrictions compared with regular inmates, his lawyer Mr. Vadim Kobzev said.