Prosecutors said her killing was probably linked to her work.
Former colleagues of Politkovskaya's at the Novaya Gazeta newspaper have said they suspect the murder was linked to a report she was preparing into allegations of torture in Chechnya.
She made regular trips to report on the Kremlin's operations against Chechen fighters and her reporting attracted the attention of officials and the security forces.
On one trip to Chechnya, she said she was arrested and held in a pit in Chechnya for three days.
She also received numerous death threats.
Anna Usachyova, a spokeswoman for Moscow City Court, said a judge had approved the detention of eight people "on the basis of suspicion that they are connected to the murder".
She did not give details on the other two suspects.
|Politkovskaya was shot dead at her apartment |
building in Moscow last October [File: AP]
The killing drew a wave of international condemnation and prompted concerns about media freedoms in Russia.
More than 80 journalists in Russia have been murdered because of their jobs since 1993, according to the International Federation of Journalists.
Jonah Hull, Al Jazeera's correspondent in Moscow, said: "She was a massively admired figure here in Russia and internationally.
"Among independent media groups her death caused uproar ... her writings were well known in Europe, the United Kingdom and the United States."
Putin said last December that everything possible was being done to find and punish her killers.
"The best professionals in Russia's law enforcement are investigating this crime and we already have certain results," he said.
A prominent campaigner for press freedom expressed scepticism that prosecutors were any closer to convicting Politkovskaya's killers.
"The murders of journalists in the past 14 years have been so poorly investigated that it's hard to have any faith in this," Oleg Panfilov, head of the Centre for Journalism in Extreme Situations, told Reuters news agency.
"I suspect it's connected with the fact that the one-year anniversary of [her] death is coming up.
"People will ask 'Where are the killers?', and this way they can say that the case is closed and suspects have been detained."