Ukraine crisis: Peaceful negotiations 'futile'
Efforts to resolve Ukraine's unrest in the capital Kiev by peaceful means are "futile", the interior ministry says.
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 activists tried to seize the energy ministry.
Four protesters and a policeman are reported to have died in protests that began last year after the government's rejection of a treaty with the EU.
A 45-year-old protester is said to have died in a Kiev hospital on Saturday, after sustaining injuries in earlier violence.
The crisis escalated this week when two activists were killed during clashes with police, and another was found dead with torture marks in a forest near the capital.
On Friday, anti-government demonstrations spread beyond the capital, with protesters now occupying several regional government buildings.
President Viktor Yanukovych earlier promised to make concessions to try to end the country's crisis.
He pledged to amend anti-protest laws and reshuffle the cabinet.
But opposition leader Vitaly Klitschko said the protesters now wanted the president to resign.
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.
"Our calls have not been heeded and a truce is being violated."
He also accused activists of shooting a police officer and kidnapping three others - allegations denied as "false and dangerous" by protest leaders.
The statement came after fresh violence erupted overnight between protesters and riot police in Kiev.
Meanwhile, activists briefly occupied the first floor of the energy ministry's main building in central Kiev.
Describing the takeover as "an act of terrorism", Energy Minister Eduard Stavytsky 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 told journalists.
The activists said it had been a temporary takeover to prove that no government building was completely secure, the BBC's Duncan Crawford, in Kiev, reports.
Protesters have also seized a number of government buildings in other Ukrainian cities, particularly in the west, which has traditionally favoured closer ties with Europe.
- In the western city of Ivano-Frankivsk, some 1,500 protesters occupied the regional administration and barricaded themselves in the building. They are now demanding that the local governor should resign immediately.
- In Chernivsti, also in the west, crowds stormed the governor's office as police tried to protect the building. People shouted "Shame on you!" and "Resign!"
- In Lutsk, in the north-west, a big demonstration was being held outside the local administration.
- Regional offices were being blockaded in the western city of Uzhgorod and unrest was reported in the eastern city of Sumy.
- In Lviv, protesters have built barricades around the governor's office that they seized on Thursday. There were also reports that some members of the special police, Berkut, were resigning.
The EU's Enlargement Commissioner, Stefan Fuele, held separate talks in Kiev with the president and opposition leaders on Friday.
Mr Fuele said the EU would assist both sides in "de-escalating the situation and finding a way out of the crisis".
The demonstrations were initially triggered by the last-minute decision of Mr Yanukovych's government to ditch a proposed association and free trade deal with the EU in November - under heavy pressure from neighbouring Russia.
But the protests later widened their demand to include the fight against what activists say are widespread government corruption and abuse of power.
The authorities deny the allegations.
Mr Yanukovych has vowed to use "all legal means" if a solution to the crisis were not found.