Mrs Politkovskaya was shot in her apartment building in an Oct 2006 killing that investigators have linked to her reporting. She exposed human rights abuses in Chechnya and was critical of the Kremlin.

The killing sparked worldwide outrage and Western governments' demands for an independent and objective investigation.

Four men charged in connection with the killing are to go on trial next week. But the suspect identified by authorities as the triggerman remains at large. Investigators have not said who they believe ordered the killing.

Mrs Politkovskaya's son Ilya Politkovsky told The Associated Press that holding regular meetings in his mother's honour was crucial.

'These are very important,' Mr Politkovsky said. 'Then we have the court case coming. We will see what will happen. It is all very important,' he said.

The suspects to face trial are Sergei Khadzhikurbanov, a former police officer with Moscow's anti-organised crime unit and brothers Ibragim and Dzhabrail Makhmudov. All deny any guilt.

Because the fourth suspect, Pavel Ryaguzov, is a former Federal Security Service office, the case will be heard at a Moscow military court. Ryaguzov is not accused of direct involvement in the killing but is being tried simultaneously because of his links to Khadzhikurbanov.

Chief investigator Petros Garibyan told Novaya Gazeta in an interview timed to coincide with the anniversary that video surveillance tapes showed the killing had been meticulously planned.

The suspects, he said, were seen entering Mrs Politkovskaya's central Moscow apartment building several times before the murder. A third brother, Rustam Makhmudov, who authorities believe pulled the trigger, even held the door open for Mrs Politkovskaya when he was leaving the building and she was entering, Garibyan said.

Tuesday's crowd huddled under umbrellas, encircled by hundreds of police. Former chess champion turned opposition activist Garry Kasparov and opposition politicians Mikhail Kasyanov and Boris Nemtsov planned to address the gathering. -- AP