Hundreds of riot police have surrounded a park in Russia's fourth-largest city before what's expected to be a third consecutive day of protests against building a new cathedral.

Local media in the city of Yekaterinburg reported on Wednesday that riot police swarmed the park, which has become the epicenter of the protests. Several thousand rallied on Monday followed by hundreds of demonstrators on Tuesday.

Several hundred people have gathered again on Wednesday, after construction workers started building a new, sturdy fence to replace the chain-link fence that the protesters brought down a day earlier.

Opponents of the cathedral say the building would take away green and recreational spaces needed by residents of a city with 1.5 million people.