An adviser to the president of Ukraine, Andriy Portnov, believes that opposition leaders are responsible for the ongoing confrontation between the anti-government protesters and police in the center of Kyiv.

"We believe that representatives of the opposition political forces bear personal responsibility for the ongoing actions on Hrushevskoho Street," he said at a briefing on Tuesday.

He suggested that the opposition leaders "have in fact associated themselves with the actions of the people who are doing what we see on Hrushevsky Street today."

Portnov also laid part of the blame for the unrest on some international institutions and foreign officials whose actions, as he put it," legitimated [the protesters'] unlawful and illegal actions."

Portnov is one of the government officials involved in negotiations with the opposition on settling the crisis.