Hundreds of protesters are clashing with riot police in the center of the Ukrainian capital, after the passage of harsh anti-protest legislation.

A group of radical activists began attacking riot police with sticks, trying to push their way toward the Ukrainian parliament building, which has been cordoned off by rows of police and buses.

Stun grenades were used and smoke was seen above the crowd. Opposition leader Vitali Klitschko tried to stop the protesters from attacking police.

The clashes occurred Sunday shortly after tens of thousands rallied on Kiev's main square, as part of anti-government protests that have rocked Ukraine for two months.