Russian police forcibly detained nearly 700 people attending a protest in Moscow on Saturday to demand free elections, including prominent activist Lyubov Sobol, after authorities warned the demonstration was illegal.

Police removed Sobol from a taxi and bundled her into a van minutes before the start of what anti-Kremlin activists described as a peaceful walk to protest against the exclusion of their candidates from an election next month.

Soon after the start of the protest, a Reuters reporter saw several hundred people milling around at one of the designated protest points in central Moscow. Minutes later, a line of riot police began to squeeze people out of the area.