Leonid Kravchuk has urged both sides to find a
compromise solution to end the crisis
Ukraine's first post-independence
president has warned the country is on the "brink of civil war" as parliament
debates an amnesty for protesters.
Leonid Kravchuk, president from 1991 to 1994, opened the debate in parliament by urging everyone involved to "act with the greatest responsibility".
President Viktor Yanukovych wants any amnesty conditional on demonstrators leaving official buildings.
The opposition has so far ruled this out and is demanding early elections.
On Tuesday, Prime Minister Mykola Azarov and his cabinet resigned after months of protests.
Parliament also scrapped a controversial anti-protest law in the biggest concession yet to opposition protesters.
'Compromise'
Leonid Kravchuk told lawmakers that "all the world acknowledges and Ukraine acknowledges that the state is on the brink of civil war".
"It is a revolution. It is a dramatic situation in which we must act with the greatest responsibility," he said in an emotional address that earned him a standing ovation.
"We need to ease the confrontation between the sides and agree a plan to solve the conflict. We need to work on this plan step by step to ease the confrontation".
To underline the importance of the session, former presidents Leonid Kuchma and Viktor Yushchenko were also present.
Continue reading the main story
30 Nov: Riot police detain dozens of anti-government protesters in a violent crackdown in Kiev
17 Dec: Russia agrees to buy $15bn of Ukrainian government bonds and slash the price of gas it sells to the country
16 Jan 2014: Parliament passes law restricting the right to protest
22 Jan: Two protesters die from bullet wounds during clashes with police in Kiev; protests spread across many cities
25 Jan: President Yanukovych offers senior jobs to the opposition, including that of prime minister, but these are rejected
28 Jan: Parliament votes to annul protest law and President Yanukovych accepts resignation of PM and cabinet
Ukraine unrest - key dates
21 Nov 2013: Ukraine announces it will not sign a deal aimed at strengthening ties with the EU30 Nov: Riot police detain dozens of anti-government protesters in a violent crackdown in Kiev
17 Dec: Russia agrees to buy $15bn of Ukrainian government bonds and slash the price of gas it sells to the country
16 Jan 2014: Parliament passes law restricting the right to protest
22 Jan: Two protesters die from bullet wounds during clashes with police in Kiev; protests spread across many cities
25 Jan: President Yanukovych offers senior jobs to the opposition, including that of prime minister, but these are rejected
28 Jan: Parliament votes to annul protest law and President Yanukovych accepts resignation of PM and cabinet
Parliament is considering an amnesty for the scores of
protesters who have been detained since demonstrations began in November.
The presidency accepts an amnesty only on condition that the demonstrators leave the government buildings they are occupying, take down their barricades and leave the streets - something the opposition rejects.
Lawmakers, in an emergency debate on Tuesday, voted to repeal anti-protest legislation, which among other measures banned the wearing of helmets by protesters and the blockading of public buildings.
The anti-protest law, passed less than two weeks earlier, fuelled major protests around the country and deadly clashes with the police.
Prime Minister Azarov said on Tuesday he was stepping down to create "social and political compromise". He has been replaced on an interim basis by his deputy, Serhiy Arbuzov.
Correspondents say Mr Azarov was deeply unpopular with the opposition, who accused him of mismanaging the economy and failing to tackle corruption.
Members of Mr Azarov's cabinet also resigned, but they can remain in their posts for 60 days until a new government is formed.
Foreign 'interference'
Both US President Barack Obama and German Chancellor Angela Merkel have separately underlined their support for the demonstrators.
Mr Obama, in his State of the Union address, said: "In Ukraine, we stand for the principle that all people have the right to express themselves freely and peacefully, and have a say in their country's future".
Steve Rosenberg visits Kiev's "protest town", which is equipped
with food stalls, a church tent, and a makeshift hospital
The White House on Tuesday said Vice-President Joe Biden had spoken by telephone to President Yanukovych and praised the "progress made".
Meanwhile, both the European Union's High Representative for Foreign Affairs, Catherine Ashton, and Enlargement Commissioner Stefan Fuele have arrived in Kiev for talks with the leadership.
Russia's President Vladimir Putin on Tuesday criticised what he called foreign "interference" in Ukraine, saying: "I think that the Ukrainian people are capable of solving this on their own."
"I can only imagine how our European partners would respond if in the heat of a crisis in a country like Greece or Cyprus, our foreign minister would appear at one of their anti-European rallies and begin addressing them," he said at the end of an EU-Russia summit in Brussels.
Protests have spread in recent days across Ukraine - even to President Yanukovych's stronghold in the east - and official buildings in several cities have been occupied.
At least five people have been killed in violence linked to the protests.
Mr Yanukovych was democratically elected in 2010 and appeared to be steering the former Soviet state towards EU integration until he rejected a planned trade deal with the bloc just days before it was due to be signed last November.
His decision to favour instead a $15bn (£9bn) bailout from Russia to bolster the ailing public finances angered many EU supporters in Ukraine.
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