None of the four defendants being tried is charged with being the actual killer and the journalist's family and supporters have expressed deep scepticism over the process.

More than two years after Politkovskaya was shot dead, the authorities have failed to identify the hitman who pulled the trigger or those who ultimately ordered the murder.

"I don't have any hope that the name of the person who ordered the killing will be revealed," Ilya Politkovsky, the journalist's son, said in advance of Monday's court hearing.

"The people who will be tried don't have direct contact with him. It's a criminal group that did this for the money."

More defendants

In addition to Pavel Ryaguzov, a former FSB agent who is suspected of providing Politkovskaya's home address to the killer, three other defendants are standing trial.

Two of them, Dzhabrail and Ibragim Makhmudov, are Chechen brothers accused of following her in her last weeks.

Politkovskaya was killled as she returned to her apartment in Moscow in 2006 [AFP]

They are brothers of Rustam Makhmudov, the man said by investigators to have actually shot Politkovskaya in the stairwell of her apartment building in October 2006.

Makhmudov has never been found and is said by investigators to have fled the country.

The fourth defendant is Sergei Khadzhikurbanov, a former police investigator from the Moscow police's organised crime unit.

The masterminds of the presumed contract killing have never been identified, despite a statement in October 2006 by then-president Vladimir Putin that Politkovskaya's killing was "an unacceptable crime that cannot go unpunished".

Kremlin criticised

Politkovskaya, aged 48 when she died, was a writer of books and articles that fiercely criticised Putin, notably for abuses committed by Russian forces during the second Chechen war, which took place under his watch.

Her killing, as she returned home carrying bags of groceries from a shopping trip, sparked outrage internationally and among opposition groups in Russia, with some critics pointing the finger of blame at the Russian leadership.

In comments days after her death, Putin promised the killers would be punished but he also offended Politkovskaya's supporters by saying her impact on Russian life had been minimal.

The Committee to Protect Journalists, a New York-based media freedom organisation, ranks Russia as the third dangerous country in the world for journalists after Iraq and Algeria, with 49 journalists killed since 1992.