LONDON — A Moscow court on Wednesday night outlawed organizations founded by Russian opposition leader Alexei Navalny, including the Anti-Corruption Foundation (FBK), by labeling them "extremist," drawing swift condemnation from the United Kingdom and the United States.

The Moscow City Court’s ruling, effective immediately, prevents people associated with Navalny’s foundation and his sprawling regional network from seeking public office. Many of Navalny’s allies had hoped to run for parliamentary seats in the Sept. 19 election, the Associated Press reported.

In a statement posted on Instagram soon afterward, Navalny denounced the hearing as a travesty of justice and vowed to continue defying the Kremlin.

“When corruption is the foundation of the government, fighters against corruption are cast as extremists,” the statement said. “We will not abandon our goals and ideas. It’s our country and we don’t have another one.”

Condemning the Russian court’s ruling, UK Foreign Secretary Dominic Raab said: “Today’s ruling that the anti-corruption foundation FBK is an extremist organization is perverse. It is another Kafka-esque attack on those standing up against corruption and for open societies, and is a deliberate attempt to effectively outlaw genuine political opposition in Russia.”

"We condemn today’s decision by a Moscow court to designate as “extremist” three organizations affiliated with imprisoned opposition figure Aleksey Navalny," Ned Price, the spokesman of the US Department of State, was quoted as saying in a press statement on Wednesday.

"This designation puts staff members, volunteers, and thousands of supporters across Russia at risk of criminal prosecution and imprisonment for exercising fundamental human rights guaranteed by the Russian Constitution, and it further restricts the ability of opposition candidates to appear on the ballot in the September Duma elections. With this action, Russia has effectively criminalized one of the country’s few remaining independent political movements," the US State Department's statement read.

"We urge Russia to cease the abuse of “extremism” designations to target nonviolent organizations, end its repression of Mr. Navalny and his supporters, and honor its international obligations to respect and ensure human rights and fundamental freedoms. The Russian people, like all people, have the right to speak freely, form peaceful associations to common ends, exercise religious freedom, and have their voices heard through free and fair elections," the statement added.

Navalny, Putin’s political rival, was arrested in January upon returning from Germany, where he spent five months recovering from a nerve agent.

In February, the Russian opposition leader was given a 2 1/2-year prison term for violating the terms of a suspended sentence from a 2014 embezzlement conviction that he dismissed as politically motivated. — Agencies