MOSCOW -- Tens of thousands of people rallied Saturday against the exclusion of some city council candidates from Moscow's upcoming election, turning out for one of the Russian capital's biggest political protests in years.
After the rally, which was officially sanctioned, hundreds of participants streamed to an area near the presidential administration building to continue with an unauthorized demonstration. They were confronted by phalanxes of riot police and the arrest-monitoring group OVD-Info said 136 people were detained.
The rally was the fourth consecutive weekend demonstration in Moscow over the local election. The determined opposition has prompted protests in other cities, reflecting widespread frustration with Russia's tightly controlled politics.
The protest attracted some 50,000 people, said Beliy Schetchik, an organization that counts public meeting attendance.
OVD-Info also said 86 people were arrested Saturday in St. Petersburg at an unsanctioned demonstration in support of the Moscow protests.
Unlike the previous two Moscow rallies, where police harshly dispersed the crowds and detained thousands of demonstrators, Saturday's gathering in a neighborhood with relatively few passers-by was officially sanctioned.
It was held on a street flanked by high buildings and sandwiched between two busy thoroughfares.
Lyubov Sobol, one of the city council candidates denied a place on the ballot and a spearhead of the election protest, was among those detained in Moscow on Saturday.
A video on Sobol's Twitter feed showed officers breaking into her office as she demanded an explanation from them.
Small related protests also were reported in several Siberian cities on Saturday.