Russian forces seized the building of Kherson city council in southern Ukraine, Ukrinform news agency reported Monday, citing Kherson mayor Ihor Kolykhaiev.

"Tonight, armed men entered the building of the Kherson City Council, took away the keys, and replaced our guards with their own," Kolykhaiev said.

Last week, Ukrainian Defense Ministry's spokesman Olexandr Motuzyanyk said Russia is preparing to hold a "referendum" in the Kherson region on joining Russia.

Ukrainian President Volodymyr Zelensky said that Kiev would withdraw from peace negotiations with Moscow if Russian forces hold pseudo-referendums in the areas they captured in Ukraine.