FILE PHOTO: People lay flowers next to a portrait of slain journalist Anna Politkovskaya on the sixth anniversary of her death, at her block of flats in central Moscow October 7, 2012. REUTERS/Sergei Karpukhin

PARIS (Reuters) - The European Court of Human Rights on Tuesday ordered Russia to pay 20,000 euros ($23,442) in damages to relatives of murdered investigative journalist Anna Politkovskaya, saying it had failed to carry out an effective investigation into her killing.

Politkovskaya, a critic of the Kremlin, was shot dead in her apartment block in Moscow in 2006 in a killing opposition leaders blamed on the Kremlin. Russian authorities denied any role in her death.

In response to the decision by the Strasbourg-based court, the Russian Justice Ministry said on its website that the ruling had not taken effect and could be appealed against by the ministry within three months.

The court, which polices the European Convention on Human Rights, said in its ruling: “The State had failed to abide by its obligations ... to carry out an effective investigation and the length of the proceedings had been too long.”

“The Court found in particular that while the authorities had found and convicted a group of men who had directly carried out the contract killing of Ms Politkovskaya, they had failed to take adequate investigatory steps to find the person or persons who had commissioned the murder.”

Politkovskaya’s killing drew attention to the risks faced by Russians who challenge the authorities and deepened Western concerns for the rule of law under President Vladimir Putin, who was then serving his second term.

Five men were convicted in 2014 of her murder. The defendants were three Chechen brothers, one of whom was accused of shooting Politkovskaya in the lobby of her Moscow apartment building on October 7, 2006, as well as their uncle and a former police officer. In December 2012 another former policeman had also been found guilty in her murder.

Rights activists and relatives of Politkovskaya have said that justice will not be done until those who ordered her contract-style killing are identified and convicted.

($1 = 0.8532 euros)