Minister Vitaliy Zakharchenko said negotiations with the protesters had failed. He blamed "radical groups" for the unrest, adding protesters had arms.

The comments came as protesters tried to seize the energy ministry. Officials said it was "an act of terrorism".

The interior minister said the opposition was no longer able to control "radical forces" and was putting civilians in danger.

"The events of the last days in the Ukrainian capital have shown that our attempts to solve the conflict peacefully, without recourse to a confrontation of force, remain futile," Mr Zakharchenko said in a statement on Saturday reports GHN based on information released by BBC.

"Our calls have not been heeded and a truce is being violated."

He also accused protesters of shooting a police officer and kidnapping three others.

Meanwhile, Energy Minister Eduard Stavytsky said around 100 activists had attempted to take over the ministry's main building in central Kiev.

He said the protesters left after he spoke to them, but were still blocking the building's entrance.

"What is taking place is a direct threat to the whole Ukrainian energy system," he was quoted as saying by the Reuters news agency.

Protesters have also seized a number of government buildings in other Ukrainian cities.