One of two suspects arrested for the high-profile killings of a human rights lawyer and journalist who were gunned down in Moscow in January has confessed, his lawyer said Friday.

The double murder of Stanislav Markelov, a lawyer who had exposed abuses by the Russian army in Chechnya, and Anastasia Baburova, a reporter at opposition newspaper Novaya Gazeta, was internationally condemned.

But the motive of Nikita Tikhonov, 24, who was this week charged with the murders along with Yevgenia Khasis, for killing the lawyer was "personal and in no way linked to his professional activities," lawyer Evgeni Skirpelev said.

Tikhonov "regretted that she (journalist Baburova) was next to the lawyer" when they were shot on January 19, the Interfax news agency quoted Skirpelev as saying.

Tikhonov also denied an accusation from the head of the FSB security service, Alexander Bortnikov, that he was a member of an extreme nationalist group, which Bortnikov said was amassing weapons and had been implicated in a racist murder.

Tikhonov also insisted that he had acted alone in the killings, the lawyer also told Moscow's radio Echo.

The Kommersant newspaper had reported that investigators believe Khasis tailed the victims and informed Tikhonov on their whereabouts.

The masked gunman managed to flee after the shootings, carried out in broad daylight on a busy street in the Russian capital.

The arrests had been cautiously welcomed by human rights groups, who complain that many killings of Russian journalists and activists go unsolved.