The United States is considering a range of options to respond to Ukraine's crackdown on opposition protests, including possible sanctions, the State Department said Wednesday.

"We are considering policy options, there obviously has not been a decision made, sanctions are included but I am not going to outline specifics," spokeswoman Jen Psaki told reporters.

Ukraine's President Viktor Yanukovych on Wednesday vowed not to use force against peaceful protesters and urged the opposition to sit down for talks after several dozen were injured in fresh clashes with riot police.

"For the sake of achieving compromise I am calling on the opposition not to reject (talks), not to follow the path of confrontation and ultimatums," Yanukovych said in a statement.

EU foreign affairs head Catherine Ashton on Wednesday condemned the use of force against pro-EU demonstrators in Kiev after police tried and failed to disperse them overnight.

"I am deeply concerned about last night's action taken by riot police," Ashton said on a visit to the Ukrainian capital.

Ukrainian demonstrators on Wednesday forced security forces to retreat after a failed pre-dawn raid on their protest camp, in a blow to the authority of President Viktor Yanukovych after nearly three weeks of rallies against his rule.

International pressure mounted on the embattled leader with U.S. Assistant Secretary of State Victoria Nuland visiting the protesters in Kiev and telling the president the attempted police crackdown was "inadmissible."

Ukrainian President Viktor Yanukovych on Tuesday met his three predecessors in a bid to defuse an escalating standoff with protesters, as several demonstrators were injured in new clashes with the security forces.

With concern growing over the risk of an even bloodier confrontation between police and protesters, EU foreign policy chief Catherine Ashton was to arrive for talks in Kiev, where a top U.S. State Department diplomat was already.

Ukraine Opposition Party Says Kiev HQ Stormed, Police Deny

The party of Ukraine's jailed opposition leader Yulia Tymoshenko's said on Monday that riot police had stormed its headquarters in the capital Kiev, although the police issued a quick denial.

The European Union's top foreign policy official, Catherine Ashton, will travel to Ukraine on Tuesday for a two-day visit after hundreds of thousands of demonstrators protested against the rejection of an EU pact, the Commission said.

"She's expected to meet all the main stakeholders on both sides ... as well as civil society," a commission spokeswoman told a regular news briefing on Monday.

Pro-EU Ukrainian demonstrators on Monday kept up their protest against President Viktor Yanukovych after symbolically toppling the statue of the Soviet Union's founder Vladimir Lenin during a gigantic rally in central Kiev.

Hundreds of protestors braved early morning sub-freezing temperatures to maintain the open-ended demonstration on Independence Square in Kiev while others staffed barricades thrown up the day earlier around key government buildings.

United Nations Secretary-General Ban Ki-moon called Ukrainian President Viktor Yanukovych on Sunday to urge for dialogue with his rivals as large-scale protests gripped Kiev, the U.N. said.

A U.N. statement said Ban "expressed his grave concern about the situation in Ukraine, emphasized that there must be no resort to violence and appealed for peaceful dialogue among all parties concerned."

Ukrainians protesting against the government's rejection of a key pact with the European Union on Sunday toppled the statue of Russian revolutionary leader Vladimir Lenin in central Kiev, police said.

"People in masks toppled the statue of Lenin," a police spokeswoman told Agence France Presse, saying they brandished the flag of Ukraine's nationalist Freedom Party and threw flares. Lenin, the founder of the Soviet state, is a figure of hate for Ukrainian nationalists.