MOSCOW - RUSSIAN police on Friday detained several opposition leaders among nearly 120 protesters during New Year's Eve rallies held in central Moscow and Saint Petersburg, news reports said.

Moscow authorities allowed the opposition to stage a traditional end-of-month demonstration to assert their right to gather under the Russian constitution.

The 300-strong crowd chanted slogans in support of the jailed Kremlin critic and former oil tycoon Mikhail Khodorkovsky, whose jail term was extended by six years on Thursday, and called for broader political freedoms, news reports said.

But several opposition leaders, including former first deputy prime minister Boris Nemtsov, broke through police lines, prompting their immediate arrest, the RIA Novosti news agency reported.

Police also detained Eduard Limonov, an opposition writer and leader of the radical National Bolshevik Party, near his Moscow home about an hour before he and his supporters were to hold an unsanctioned rally alongside the authorised one.

Shortly after his arrest, a court sentenced Limonov to 15 days in prison for insulting police during his detention, a court spokesman, Pyotr Chenik, was quoted as saying by the RIA Novosti news agency.