MOSCOW — A top ally of Alexei Navalny vowed Tuesday to keep up the fight to free the jailed Russian opposition leader and his battle to influence this year’s parliamentary election despite a government crackdown on nationwide protests and its attempts to create a climate of fear.

U.S. officials said President Joe Biden raised concerns about Navalny’s arrest in his call Tuesday with Russian President Vladimir Putin, and the G7 foreign ministers also criticized the jailing of Navalny and the demonstrators demanding his release.

Lawyer and politician Lyubov Sobol told a news conference that Navalny’s Foundation for Fighting Corruption and his team’s regional offices will continue to operate even amid the “arrests of our followers and allies, open criminal probes (and) criminal probes that are yet to come.”

Sobol, herself under investigation on criminal charges of trespassing that she insists are bogus, said she is not afraid of being arrested and doesn’t plan to leave the country.

“It would be hard to say that I’m prepared for it, but silence, fear and indifference are more dangerous,” she told reporters.

Navalny, President Vladimir Putin’s fiercest critic, was arrested and jailed earlier this month after returning to Russia from Germany, where he had spent nearly five months recovering from a poisoning with a deadly nerve agent that he blames on the Kremlin. Russian authorities deny the accusations.

The politician faces a prison term, with authorities accusing him of violating the terms of a 2014 conviction for fraud, a prosecution that he says was politically motivated.

On Saturday, nearly 4,000 people were detained across Russia during nationwide protests that drew tens of thousands demanding Navalny’s release, according to OVD-Info, a human rights group that monitors political arrests.