Protesters have clashed with police in central Kiev, Ukraine amid tensions over proposed changes to the constitution, Tuesday.
Thousands have attacked the ruling-party headquarters trying to march on parliament and have been blocked by lines of police vehicles, BBC news reported.
Tensions have been reported inside parliament, too where opposition MPs are pushing for a vote on replacing the constitution.
Some protesters are hurling cobblestones at police, others are throwing smoke bombs, while police are responding with stun and smoke grenades and rubber bullets.
Several people have been injured, both protesters and police officers, local media reported.
Inside parliament about 50 opposition MPs have blocked the parliamentary rostrum in protest after parliamentary staff refused to register their resolution on reinstating the 2004 constitution, Ukrainian Interfax reported.
The opposition has been demanding for weeks the return of the 2004 constitution, which would curb some of President Yanukovych's powers he has gained since his election in 2010.
The changes would mean that parliament, rather than the president, would appoint the prime minister and most cabinet members, as well as regional governors.
The move could also lead to early presidential elections, which has been a key demand of the opposition.
Meanwhile, Russia is expected to follow up on its promise to buy out Ukrainian government bonds by making a USD 2 B tranche this week.
Russian President Vladimir Putin and his Ukrainian colleague Viktor Yanukovych agreed on a USD 15 B loan in the form of buying Ukrainian government bonds, when the two met in December.
The move is seen as an attempt to outmaneuver the West, which is also preparing a financial stimulus package to Ukraine, but the terms for it remain unclear.