Ms Politkovskaya was found dead outside her Moscow apartment block

Colleagues have been paying tribute to Russian investigative reporter Anna Politkovskaya and reflecting on the possible motives behind her murder.

All the main Russian TV and radio bulletins led with news of the death of the Novaya Gazeta reporter, widely seen as a thorn in the side of the authorities for her reports exposing abuses in the Chechen conflict and in government at large.

'Courageous'

State TV ran sombre reports noting the acclaim Ms Politkovskaya had earned for her reporting on such events as the Moscow theatre siege in 2002 and the Beslan school siege two years later.

She was the conscience of Russian journalism Oleg Panfilov

She was a "bold and courageous" journalist, Channel One observed.

More emotional and forthright assessments of Ms Politkovskaya's career came from colleagues on the liberal wing of the Russian media.

"She was the conscience of Russian journalism," the director of the Centre for Journalism in Extreme Situations, Oleg Panfilov, told independent radio station Ekho Moskvy.

"It was Anna's name that came to mind when I was asked if honest journalism exists in Russia."

The general secretary of the Russian Union of Journalists, Igor Yakovenko, described Ms Politkovskaya's death as a "blow to the very heart of Russian journalism".

She was a "fearless reporter", he added.

For Ekho Moskvy's Yuliya Latynina, Ms Politkovskaya's death was of even greater significance because of her tireless campaigning.

"She was not just a journalist, but a human rights activist, who always stood on the side of the weak and downtrodden," Ms Latynina told listeners of her regular Saturday evening phone-in programme.

"She never wrote a word she did not believe in."

Chechen link

Ms Latynina also voiced her belief the murder was linked to events in Chechnya, which had been the focus of Ms Politkovskaya's recent reporting.

Her deputy editor at the Novaya Gazeta newspaper, Vitaly Yaroshevsky, said Ms Politkovskaya had been working on an article about torture in Chechnya, which was to have been published on Monday.

It is a contract killing committed for political motive Igor Yakovenko

The newspaper's website said on Sunday that, whoever may ultimately have been responsible for the murder, some link to Chechnya was clear.

Whatever the precise motive, few were in any doubt the killing was linked to Ms Politkovskaya's work.

"This is a rare case where there is no doubt whatsoever about what type of murder this is," Mr Yakovenko told the business channel RBK TV.

"It is a contract killing committed for political motives," he added.

Probe doubts

But while media commentators were sure about the political nature of the killing, there was less confidence about the prospects for a conclusive investigation.

From now on, anything can be done in Russia Yuliya Latynina

Ekho Moskvy's chief editor Alexei Venediktov reminded viewers of the NTV channel that there had not been a successful prosecution for any of the four most high-profile journalist killings of the past 10 years, while Ms Latynina was even more categorical.

"They won't find the killers," she declared.

Ms Latynina ended her Ekho Moskvy programme on an equally gloomy note, observing bitterly that "this is a sign that from now on, anything can be done in Russia".

BBC Monitoring selects and translates news from radio, television, press, news agencies and the internet from 150 countries in more than 70 languages. It is based in Caversham, UK, and has several bureaux abroad.