(AGI) Moscow, March 1 - Thousands of protesters carryingbanners saying "I'm not afraid" gathered in Moscow on Sunday ina march to commemorate Boris Nemtsov, the leader of the liberalopposition, who was shot dead only a short distance from theKremlin on Friday night. Entire families, including elderlypeople marching alongside the young, slowly marched through thestreets holding posters with the image of Nemtsov, who was shotdown after leaving a restaurant in the centre of Moscow. Themarch started with a streamer which said "Heroes don't die" andcontinued in a serene atmosphere, recording no accidents. Theopposition party attributed responsibility for the death of thepolitician to the climate of intollerance towards dissidentsthat prevails in the Country. "The government created anatmosphere of aggression and hatred toward critics, depictingmembers of the opposition as traitors," said Gennady Gudkov, anopposition activist, before the march kicked off. "If wesucceed in putting an end to this climate of hatred, then wewill have the possibility to change Russia. Otherwise, we riska generalised civil war," he said. The Moscow police put up animpressive security system to assure the safety of participantsin the march, which was authorised by the City Council. Themarch also skirted the Kremlin bridge near which 55-year-oldNemtsov was killed. There is controversy over the number ofparticipants in the march. There are no confirmed figuresalthough organisers spoke of over 70,000 participants while thepolice said there were 16,000. Russian authorities have offereda 3 million ruble reward (almost 45,000 euros) to anybodyproviding "useful information" on the murder of the liberalopposition leader, announced the Inquiry Committeeinvestigating the case. The Committee previously addressed anappeal to anyone who might have witnessed the shooting or mighthave information on the case, inviting all citizens tocollaborate with justice, even anonymously. The Committeeinformed that it intends to again interrogate Anna Duritskaya,the 23-year-old Ukrainian model who was walking with Nemtsovwhen he was hi by four gun shots on Friday night. The Russianpolice arrested Alexei Goncharenko, a Ukrainian MP, during themarch, the parliamentarian announced on Facebook: "Police havedetained me. I did not shout anything, did not carry anybanners or flags -- they simply detained me over the T-shirt",which showed a photo of Nemtsov and the writing "Heroes neverdie". Moscow police declined to comment the arrest, which wasnonetheless confirmed by Russian State TV, and said that hewill be handed over to investigators. Goncharenko, 34, is amember of the parliamentary group supporting Ukraine'sPresident, Petro Poroshenko. According to sources of theInterfax press agency, Goncharenko could be sought by thepolice in connection to the violent clashes that took place inOdessa last May 2, when roughly 50 pro-Russian marchers died inthe fire of the city's House of Culture. In the meantime, avideo broadcast by Russia's TV Centre network showing the lastmoments of Boris Nemtsov's life is being circulated onlineworldwide. The very far-away images filmed by a camera of aweather station near the Red Square show Nemtsov approached bythe killer, who escapes on a car after shooting him. (AGI) . .