Story highlights

Kiev's police chief resigns after riot police violence against protesters, police say

Anti-government demonstrators continue to clash with security forces Sunday

Interior minister apologizes for violence, but urges protesters to behave

CNN  — 

The chief of police in Kiev, Ukraine, Valeriy Koryak, has resigned after riot police used “excessive force” against anti-government protesters, police said.

Riot police stepped in early Saturday and dispersed several hundred people who came to Independence Square in support of Ukraine’s European integration. Seven people were hospitalized and dozens arrested.

The United States condemned what it called “violence against protesters” in a statement posted online by the U.S. Embassy in Kiev.

Ukrainian Interior Minister Vitaliy Zakharchenko later apologized, saying riot police abused their power. He promised a thorough investigation.

But he also warned protesters via state television against improper behavior, saying “if there are calls for mass disturbances, then we will react to this harshly.”

A massive crowd of protesters, estimated to number at least 100,000, gathered Sunday in Independence Square. Some were seen setting objects on fire and throwing them at security forces. Others broke through a police barrier that was guarding a Christmas tree, climbed the tree and topped it with the Ukrainian flag.

CNN’s Zarifmo Aslamshoyeva contributed to this report.