Updated  - Ukrainian opposition leader Yulia Tymoshenko this evening urged President Viktor Yanukovich's opponents not to abandon their protests in central Kiev even though parliament has voted to oust him and he had fled the capital..

In an emotional speech to thousands of protesters in Kiev's Independence Square after she was carried on to a stage in a wheelchair, she said: "You have no right to leave the Maidan (square)... Don't stop yet."

Tymoshenko, a former prime minister, was released earlier today from the hospital where she had been held under prison guard for much of the time since she was convicted in 2011 on charges of abuse of office. Supporters say the case was politically motivated.

Her speech was briefly interrupted by a heckler but she later carried on addressing the crowd. Some people welcomed her speech but others whistled.

Her release was made possible by a European-brokered peace deal between her arch-rival, President Viktor Yanukovych, and the opposition.

Earlier today, the Ukrainian parliament declared President Viktor Yanukovich constitutionally unable to carry out his duties and set an early election for May 25.

Deputies in the assembly stood, applauded and sang the national anthem.

The president described the country's political crisis a coup that resembled the rise of Nazis in the 1930s.

Yanukovych said he has no intention of resigning or leaving the country but he has left the capital and is thought to be in the east of the country, where he enjoys support.

He made the coup accusation in a televised statement.

The leaders of mainly Russian-speaking regions of eastern Ukraine that are loyal to President Yanukovich challenged the legitimacy of the national parliament and said they were taking control of their territories.

The move appeared to increase the possibility of a split in the sprawling former Soviet republic of 46 million, despite denials by the leaders that this was their intention.

The Kiev parliament has passed a series of measures that would reduce the president's powers and pave the way to the formation of a national unity government and early presidential elections.

Mikhaylo Dobkin, Governor of Kharkiv region in northeast Ukraine, told regional leaders meeting in the city: "We're not preparing to break up the country. We want to preserve it."

But a resolution adopted at the meeting said: "The decisions taken by the Ukrainian parliament in such circumstances cause doubts about their ... legitimacy and legality."

It added: "The central state organs are paralysed. Until the constitutional order and lawfulness are restored ... we have decided to take responsibility for safeguarding the constitutional order, legality, citizens' rights and their security on our territories."

One speaker urged the creation of civilian patrols to restore order. Another said those gathered should fear reprisals if anti-Yanukovich protesters in Kiev seize power in the whole of the country.

With people at the meeting chanting "Russia! Russia!", the atmosphere contrasted with the mood in the capital Kiev where protesters want the Moscow-backed Yanukovich to resign.

The regions represented at the meeting - Kharkiv, Donetsk, Dnipropetrovsk, Lugansk and Crimea - have a population of 14.4 million. Most are important industrial centres and Russia's Black Sea fleet is based in the Crimean port of Sevastopol.