Human rights Briton held in Russia

The five, including citizens of Spain and Germany, were among dozens who travelled to Nizhny Novgorod for the conference, said Svetlana Gannushkina, the head of the non-governmental Civic Assistance Committee.

Police in Nizhny Novgorod, about 250 miles east of Moscow, refused to comment on Saturday about the foreigners' detention, and local officials could not be reached. Interfax news agency quoted a police official as saying the activists had been detained for breaking local registration requirements.

Meanwhile, journalists and supporters of Russia's beleaguered opposition are planning to hold ceremonies in Moscow to mark the first anniversary of the murder of Politkovskaya, a world-renowned investigative reporter and a critic of the Kremlin.

Politkovskaya had won international acclaim for her reporting of atrocities against civilians in war-scarred Chechnya.

Her death, in an execution-style killing in the entrance of her Moscow apartment building, cast a harsh light on the state of civil society and the safety of journalists and government critics under President Vladimir Putin.

Conference organisers said the foreign activists' detention was part of an official campaign to thwart the gathering, where participants planned to discuss the investigation of Politkovskaya's murder as well as the state of journalism in Russia.

Organisers said authorities had pressured the venue owners into reneging on a lease agreement and pressuring hotel administrators to block reservations from some attendees.

"This is not just the idiocy of provincial life, this is also the idiocy of the federal government," Gannushkina said.