At least 70 people have been killed during street fighting between protesters and riot police in the Ukrainian capital of Kiev, while the country's interior ministry says that 67 police officers were seized by the protesters.
A Reuters photographer saw bodies of 21 dead civilians in Independence Square, the centre of the protests, on Thursday raising the total death toll since Tuesday to over 50, according to counts by the AFP and Reuters news agencies.
The Interior Ministry announced that protesters had seized tens of police officers, saying it reserved the right to use firepower to free them.
"Radical extremists have seized 67 interior ministry servicemen," the ministry said in a statement on Thursday. "Law enforcement officials can resort to all legal means [to secure their release], including the use of arms."
In an effort to defuse the situation, the national parliament late on Thursday passed a measure that would prohibit an "anti-terrorist operation" threatened by President Viktor Yanukovych to restore order.
The measure called for all Interior Ministry troops to return to their bases but it was unclear how binding the move would be.
Presidential adviser Marina Stavnichuk was quoted by the Interfax news agency as saying the measure goes into effect immediately, but that a mechanism for carrying it out would have to be developed by the president's office and the Interior Ministry.
The country is the object of a geopolitical tug-of-war between Moscow, which sees it as the historical cradle of Russian civilisation, and the West, which says Ukrainians should be free to choose economic rapprochement with the European Union. The protests by EU-supporters in the country have been going on since late November.
The fresh deaths on Thursday came in a new eruption of clashes just hours after the country's embattled Yanukovych and the opposition leaders demanding his resignation called for a truce and negotiations to try to resolve Ukraine's political crisis.
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The interior ministry said that two policemen died from gunshot wounds sustained in the clashes and advised Kiev residents to stay indoors "because the streets of Kiev are occupied by armed and aggressive people".
Witnesses said they saw snipers firing from high spots during the clashes.
Meanwhile, the mayor of Kiev resigned from Yanukovych's ruling Regions Party in protest over the continuation of "bloodshed".
"The events happening in the Ukrainian capital are a tragedy," Volodymyr Makeyenko, the mayor of Kiev, said in a statement announcing that he is leaving Yanukovich’s ruling party.
"I have decided to resign from the Regions Party and assume personal responsibility for the livelihood of the city of Kiev."
On the diplomatic front, the EU decided to follow the US' footsteps and impose sanctions on its Eastern European neighbour.
In an emergency meeting on Thursday, the EU foreign ministers agreed to impose a travel ban and asset freeze on Ukrainian officials responsible for the violence in the country.
The US said on Wednesday that it had imposed visa bans on 20 Ukrainian government officials it considered "responsible for ordering human rights abuses related to political oppression".
Moscow slams EU
"The EU is also trying to consider the introduction of sanctions and at the same time they come to Kiev on uninvited missions," Sergei Lavrov, the Russian foreign minister, was quoted as saying during a visit to Baghdad.
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"Such actions are reminiscent of blackmail," he said according to state-run news agency RIA reported.
Russia, which has been holding back a new loan instalment until it sees stability in Kiev, has various times condemned EU and US support of the opposition demands that Yanukovich, elected in 2010, should share power and hold new elections.
The crisis in the sprawling country of 46 million, with an ailing economy and endemic corruption, has mounted since Yanukovich, under pressure from the Kremlin, decided to take a $15bn Russian bailout instead of a wide-ranging deal with the EU.