EC President Jose Manuel Barroso has sent off EU foreign policy chief Catherine Ashton to Kiev on Tuesday, saying she will try to help defuse "the very tense solution that Ukraine is living today."

The High Representative of the Union for Foreign Affairs and Security Policy is on a two-day trip to Ukraine in an attempt to mediate the political crisis in the country as the European Commission announced Monday it was taking the initiative to seek a peaceful solution of the conflict.

Ashton is to meet with representatives of the opposition, the government and civil society.

Also on Monday, she warned the Ukrainian authorities against use of force after police reportedly raided the offices of the country's main opposition party Fatherland of jailed former Prime Minister, Yulia Tymoshenklo.

Barroso has praised the demonstrators, saying they were "writing the new narrative for Europe."

Ukrainian riot police Berkut started a crackdown on pro-EU protesters in downtown Kiev overnight, dismantling protest tent camps in front of government buildings.

Police were seen forcing protesters out of two streets where, according to the Interior Ministry, they were blocking access to administrative buildings.

Scores have been injured.

Hundreds of thousands of people have been protesting in Kiev's Independence Square against the recent decision of President Viktor Yanukovych and his government to back out of a strategic deal with the EU and seek closer ties with Russia.

As tensions keep mounting, Yanukovych announced on his website that he would meet with Ukraine's three former presidents to discuss the situation: Leonid Kravchuk, Leonid Kuchma and Viktor Yushchenko.

At the same time, prosecutors called in several opposition leaders for questioning.

US Ambassador to Ukraine Geoffrey Pyatt cautioned the government against using force.

"Peaceful demonstrations must be allowed to continue. Dialogue and non-violence key, world watching. Opportunity must not be lost," he wrote on Twitter.

US Vice President, Joe Biden, has spoken over the phone to Yanukovych, expressing "deep concern" about the situation in Kiev and urged dialogue with the opposition.

"[Mr Biden] noted that violence has no place in a democratic society and is incompatible with our strategic relationship," the White House said in a statement.

On Sunday, protesters toppled a statue of former Soviet leader Vladimir Lenin and blockaded government buildings.