Moscow police detained 35 people on Friday, including opposition leader Boris Nemtsov, during a New Year's Eve rally held a few blocks from the Kremlin, Interfax reported. City authorities allowed the opposition to stage a traditional end-of-month demonstration to assert their right to gather under the Russian constitution. Demonstrators chanted slogans in support of Russia's jailed Kremlin critic and former oil tycoon Mikhail Khodorkovsky, whose jail term was extended by six years Thursday, and called for broader political reforms, news reports said. But several opposition leaders, including the former first deputy prime minister Nemtsov, broke through police lines, prompting their immediate arrest, the RIA Nosoti news agency reported. The police also detained the writer Eduard Limonov and Ilya Yashin, leader of the youth wing of the liberal Yabloko group, news reports said. Opposition leaders call regular demonstrations on the 31st day of the month in honour of Article 31 of the constitution, granting Russians freedom of assembly. Moscow authorities have until recent months refused to sanction such rallies, prompting frequent scuffles with the police. There were no initial reports of violence during Friday's demonstration. 