Russia's president, Vladimir Putin, has fired two police generals over the discredited criminal case against journalist Ivan Golunov, the Kremlin said.

Golunov, known for his investigative work probing corruption, was arrested last week after law enforcement said they found drugs on him.

His case triggered public outcry and critics said he was framed because of his work.

Police made a rare U-turn on Tuesday when they abruptly dropped the charges against Golunov and let him walk free.

READ MORE: Ivan Golunov: Russian journalist walks free after police drop criminal charges

Interior Minister Vladimir Kolokoltsev also said at the time he would ask Putin to dismiss senior police personnel involved in the case.

His arrest sparked an unusual show of media unity in Russia, with the three leading daily newspapers carrying the headline "I am/We are Ivan Golunov" on Monday.

The showing from the press is rare in Russia where journalists are routinely threatened and even murdered over their work.

Golunov's arrest provoked outrage from international media and statements of concern from the European Union and the United States.

While authorities might have hoped freeing Golunov and vowing to bring those who allegedly framed him to justice would calm his supporters, over 1,000 people marched through central Moscow on Wednesday, according to Reuters witnesses.

Russian police said they detained more than 200 people at the demonstration, including opposition politician Alexei Navalny.

WATCH MORE: Navalny among hundreds arrested at protest over Golunov's 'framing'

The number of detained was at least twice that quoted by official numbers, totalling over 400 people, Russian media reported.

Protesters chanted "Russia will be free," "Russia without Putin," and "Down with the Tsar" as police warned them not to break the law and blocked access to certain streets.

The authorities had warned protesters that their demonstration would be illegal and could pose a risk to public safety — Russian law stipulates the time and place of protests involving more than one person need to be agreed with the authorities in advance.

Golunov works for Meduza, an independent Russian language media outlet based in Latvia that describes itself as "the real Russia today."

By basing itself in an EU country, Meduza can get around censorship from Moscow, although some of its journalists live in Russia, including Golunov.