Some 70,000 protesters have gathered at Kiev's Independence Square for a new rally against embattled President Viktor Yanukovych.
After a blessing by religious leaders, rock music blared out on Kiev's Independence Square, where protesters have been camping out for months, ahead of the demonstration.
Opposition leader Vitaly Klitschko told protesters: “He (Yanukovich) says we need half a year to get a new constitution. But our people are not going to wait for half a year.
“We can change the constitution now, go back to the 2004 constitution first and then take time to draft a new constitution. But this in itself is not enough. People demand one thing - snap presidential elections,” boxer-turned-politician Klitschko told the crowd.
“A new constitution. A new president. A new government. A new country. This is what we want and we will prevail,” another opposition leader, Arseniy Yatsenyuk, said.
The ex-Soviet nation of 46 million has been thrown into disarray since November when Mr Yanukovych ditched a historic EU trade and political pact in favour of closer ties with Russia.
Since then, demonstrations and protests have continued and spread to other parts of the country.
The embattled Ukrainian leader jetted off to Russia's Black Sea resort of Sochi on Thursday to hold brief talks with Russian President Vladimir Putin on the sidelines of the opening of the Winter Olympic Games a day later.
It is unclear what the two discussed, but Mr Yanukovych had been expected to discuss the fate of the bailout, of which Russia has so far issued only one instalment of $3 billion.