U.N. High Commissioner for Human Rights Navi Pillay called Wednesday for an end to the violence in Ukraine, where clashes between police and demonstrators have left at least 25 people dead and more than 200 others wounded in the past 24 hours.

"I strongly condemn the killings and urge the government and protesters to act to defuse tensions and to take swift action to find a peaceful solution to the ongoing crisis," Pillay said.

The top U.N. official for human rights also called for "an urgent and independent investigation to establish facts and responsibilities, including the possible use of excessive force, and to ensure accountability for these deadly clashes."

The violence in Kiev, Ukraine's capital, intensified on Tuesday when protesters marched on Parliament, where lawmakers planned to debate the restoration of the 2004 constitution limiting the president's powers.

"Ukraine needs a dialogue between these opposing voices that respects the country's legal obligations, political commitments based on international human rights standards, and the recommendations made by the international human rights system," Pillay said.

The ambassadors from the EU member countries are looking at whether the bloc should impose sanctions on "those responsible for the repression" in Ukraine, Maja Kocijancic, spokeswoman for EU foreign policy chief Catherine Ashton, said.

The sanctions must be unanimously approved by the EU's 28 members and could be approved on Thursday by the bloc's foreign ministers, Kocijancic said.

Sanctions could be approved "in a relatively short time," thanks to the streamlining of the process under the Treaty of Lisbon, Kocijancic said.

The explosion of armed violence in Ukraine on Tuesday came just after the amnesty for all people arrested so far in the protests had gone into effect, a move that followed the demonstrators' abandonment of the Kiev city hall, which they had occupied in November.

Ukraine's current crisis erupted at the end of November, when President Viktor Yanukovych backed away from plans to ink a pact with the European Union and instead signed a $15 billion financial-aid package with Moscow.

Pro-Europe protesters took to the streets in downtown Kiev and began occupying administrative buildings, prompting Ukraine's Parliament, controlled by Yanukovych's allies, to pass a package of laws on Jan. 16 restricting freedom of assembly, freedom of speech and other basic rights.

Violent clashes pitting demonstrators and riot police broke out three days later and left six dead and hundreds wounded.

Ukrainian officials and opposition leaders began seeking a negotiated solution to the crisis in the wake of the bloodshed.

The talks led to the resignation of Prime Minister Mykola Azarov and the repeal of the controversial anti-protest laws, but opposition demonstrators are still demanding that Yanukovych step down in favor of early elections. EFE