MOSCOW (AP) — Police in Russia raided the home of the chief editor of an investigative news site that was recently designated as a “foreign agent,” the latest move by authorities to raise the pressure on independent media before the country's September parliamentary election.

The Insider news site chief editor Roman Dobrokhotov tweeted Wednesday that “police are knocking" on his apartment door, and his wife reported the raid to the OVD-Info legal aid group before her phone became unavailable.

A lawyer from another legal aid group, Pravozashchita Otkrytki, headed to Dobrokhotov's apartment. The group said police seized cellphones, laptops and tablets during the raid, as well as Dobrokhotov's international passport. Sergei Yezhov, a journalist with The Insider, said Dobrokhotov was supposed to travel outside of Russia on Wednesday.

Police also raided the home of Dobrokhotov’s parents, The Insider said. After the searches, Dobrokhotov was taken to a police precinct for questioning and then released.

He told reporters outside the precinct that The Insider will continue to operate despite the pressure from authorities.

“It will become more difficult to work now. I don’t have cell phones, I can’t travel and meet my colleagues — many of our investigations are international," Dobrokhotov said. "And, of course, it's serious pressure. But it’s clear that The Insider will continue to exist. Investigations will be released even if I am arrested. If they hope to halt the work of the news site, they hope in vain.”

Russian opposition supporters, independent journalists and human rights activists have faced increased government pressure ahead of the Sept. 19 vote, which is widely seen as an important part of President Vladimir Putin’s efforts to cement his rule before the 2024 presidential election.

The 68-year-old Russian leader, who has been in power for more than two decades, pushed through constitutional changes last year that would potentially allow him to hold onto power until 2036.

In recent months, the government has designated several independent media outlets and journalists as "foreign agents" — a label that implies additional government scrutiny and carries strong pejorative connotations that could discredit the recipients.

The targeted outlets include VTimes and Meduza. VTimes subsequently shut down, citing the loss of advertisers, and Meduza launched a crowd-funding campaign after encountering the same problem.

The Insider was the latest addition to the list. The news outlet, which is registered in Latvia, has worked with the investigative group Bellingcat to investigate high-profile cases, such as the nerve agent poisonings of former Russian spy Sergei Sripal and Russian opposition leader Alexei Navalny.

The Russian Justice Ministry acted under a law that is used to designate as foreign agents non-governmental organizations, media outlets and individuals who receive foreign funding and engage in activities loosely described as political.

Another law is used to outlaw groups deemed “undesirable” and makes membership in them a criminal offense. It has been used to ban 41 groups, including opposition groups, foreign NGOs and most recently, the publisher of Proekt, an online investigative media outlet.

The Justice Ministry last week also designated two Proekt journalists and three other reporters as foreign agents.

Russia used the law to levy heavy fines on U.S.-funded broadcaster Radio Free Europe/Radio Liberty for failing to identify its material as produced by foreign agents. The broadcaster has asked the European Court of Human Rights to intervene.

According to The Insider, the searches targeting Dobrokhotov may be related to a slander case launched in April following a complaint by a Dutch blogger. The Insider accused Max van der Werff of working with Russian intelligence and military services to spread false information challenging the findings of the official investigation into the downing of Malaysia Airlines Flight 17 over eastern Ukraine, which killed all 298 people on board.

The legal aid group said Dobrokhotov was a witness in a criminal case against “unidentified persons” on the charges of slander, launched over a tweet in Dobrokhotov's account that contains “disinformation about the downed Boeing MH-17.”

Earlier this week, Russian authorities blocked about 50 websites linked to the imprisoned opposition leader Navalny. The move comes just a month after a court in Moscow outlawed Navalny's political infrastructure — his Foundation for Fighting Corruption and a network of regional offices — as extremist in a ruling that prevents people associated with the groups from seeking public office and exposes them to lengthy prison terms.

Navalny, Putin’s fiercest political foe, was arrested in January upon returning from Germany, where he spent five months recovering from a nerve agent poisoning that he blames on the Kremlin — an accusation rejected by Russian officials.

In February, the politician was ordered to serve 2 1/2 years in prison for violating a suspended sentence from a 2014 embezzlement conviction that he dismissed as politically motivated.

His arrest and jailing sparked a wave of mass protests across Russia in what appeared to be a major challenge to the Kremlin. The authorities responded with mass arrests of demonstrators and criminal probes against Navalny’s closest associates.

On Wednesday, Lyubov Sobol, a top ally of Navalny and one of the few in his team who hasn't left Russia despite being prosecuted on a number of charges, said Russia's state communications watchdog Roskomnadzor demanded that Twitter take down her account.

“What is it, if not the Kremlin's hysteria ahead of the election?” Sobol wrote.

It wasn't immediately clear whether Twitter would comply with the request.

Daria Litvinova, The Associated Press