They stood like a unit from a paramilitary army, in camouflage fatigues and clutching baseball bats, their faces concealed underneath helmets and black balaclavas.

Radical activists Monday blockaded the Ukrainian justice ministry in Kiev, in a provocative move that risked derailing talks to end Ukraine's crisis and was condemned even by some within the opposition.

EU foreign policy chief Catherine Ashton is to fly to Ukraine on Tuesday, 48 hours earlier than previously scheduled, to help defuse the country's crisis, she announced Monday.

Ashton originally had been scheduled to visit Kiev at the end of the week as the European Union attempts to help mediate an end to the protest turmoil, but said in a statement: "I will fly to Kiev tomorrow (Tuesday) evening."

U.N. leader Ban Ki-moon on Monday pressed Ukraine's President Viktor Yanukovych to start a "constructive dialogue" with the opposition to end the country's deadly unrest.

U.N. spokesman Martin Nesirky said Ban highlighted his "grave concern" over the Ukraine crisis in a telephone conversation with Yanukovych.

Ukrainian President Viktor Yanukovych was on Monday holding a new and previously unannounced meeting with the three main opposition leaders aimed at resolving the country's crisis, the presidency said.

Along with senior aides, Yanukovych was meeting UDAR (Punch) party leader and world boxing champion Vitali Klitschko, Fatherland leader Arseniy Yatsenyuk, and nationalist Svoboda (Freedom) party leader Oleg Tyagnybok.

A 55-year-old man was found hanged inside the frame of a giant Christmas tree in Kiev on Monday at the main protest camp in the city, the interior ministry said.

"There are no signs of other injury on the body," the ministry said in a statement, indicating a probable suicide.

Ukraine on Monday said the introduction of a state of emergency was not yet on the agenda after radicals seized the justice ministry in Kiev in an attack that raised concerns of a derailing of talks to ease the crisis.

The Ukrainian parliament on Tuesday was due to meet to discuss concessions proposed by President Viktor Yanukovych, in a highly anticipated extraordinary session that could be a make-or-break moment to resolve the standoff.

Thousands in Kiev on Sunday mourned a protester shot dead during clashes, as a rebellion against President Viktor Yanukovych's authority spread despite sweeping concessions offered by the embattled leader.

An emotional crowd packed Saint Michael's Cathedral for the Orthodox funeral to pay their last respects to 25-year-old Mikhail Zhiznevsky, as Pope Francis prayed for dialogue in a country swept by civil strife.

Germany's foreign minister on Sunday urged Ukrainians to refrain from violence and to reach a political solution to escalating unrest.

"The daily television images from Kiev and many Ukrainian regions show that the situation is not only tense but truly serious," said the minister, Frank-Walter Steinmeier.

The unrest in Ukraine should not be seen as a battle between the East and the West, British Foreign Secretary William Hague said Sunday.

Calling for a change in the narrative Hague said free trade between Ukraine and the European Union would benefit Russia too, as he urged restraint from government forces in the face of pro-EU protests.

Pope Francis prayed Sunday for an end to violence in Kiev, calling for dialogue between the Ukraine government and opposition amid fears fierce protests could develop into a wider civil conflict.

"I hope for constructive dialogue between the institutions and civil society, and that -- without recourse to violent action -- the spirit of peace and the search for common good may prevail in the hearts of all," he told crowds gathered in St. Peter's Square for the Angelus prayers.