Protestors in Ukraine readied for a fresh mass demonstration Sunday as they ratcheted up the pressure on embattled leader Viktor Yanukovych to appoint a new pro-Western government and take a more conciliatory approach towards the European Union.

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 due to kick off at midday (1000 GMT) in the brisk cold.

The ex-Soviet nation of 46 million has been thrown into disarray since November when Yanukovych ditched a historic EU trade and political pact in favour of closer ties with old Soviet master Russia, stunning pro-EU parts of the population and sparking violent protests.

But what started out as a localised, domestic bout of unrest morphed into a titanic tussle for Ukraine's future between Russia and the West, as demonstrations continued and spread to other parts of the country.

Yanukovych is caught between the two, and while he has already yielded to some of the opposition's demands by dismissing the government, he also has to appease Russia, which has effectively frozen a much-needed $15 billion (11 billion euro) bailout until the situation clears up.

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 Yanukovych had been expected to discuss the fate of the bailout, of which Russia has so far issued only one instalment of $3.0 billion.

On Independence Square on Sunday, protesters went about their daily business as they waited for the demonstration to start, heating their tents in the cold and cooking food in big steaming vats.

"We hope that authorities will make concessions and that agreements with the opposition will bring results. Because the authorities look like Somali pirates who take hostages and then negotiate," 29-year-old Oleksandr Zaveroukha, who had come from western Ukraine, told AFP.

"We are determined to stay until the end."

Late Saturday evening, activists were seen training for the next-day protest by fighting each other on the square, some acting as riot police with shields.

Protesters a 'key wildcard'

Alex Brideau, an analyst for political risk consultancy Eurasia Group, said the actions of the protesters were a "key wildcard in the political standoff", noting that their "continued frustration with the lack of progress on their demands" was a major factor behind violence at the end of January that left at least four activists dead.

Leading Ukrainian lawmakers are expected to meet on Monday to discuss opposition proposals to slash presidential powers and return to the country's pre-2010 constitution that granted extended powers to parliament.

Yanukovych has signalled that he welcomes a discussion of the changes without committing himself to the reform.

But Ukraine's tattered economy is in ever-growing need of assistance amid sliding domestic production and dwindling foreign reserves.

Moscow is already demanding the repayment of a $3.3 billion debt that Ukraine has piled up since last year for Russian natural gas imports on which the country's industries and households depend.

Putin's bailout would slash the future price of Russian gas imports by a third -- a huge relief for the economy that analysts believe should help revive stalled growth.

But Russian Economy Minister Anton Siluanov warned Saturday that Moscow would need at least a partial down payment on the outstanding gas bill before the terms of its Ukrainian package are restored.

Currency crisis

The protracted crisis has seen Ukraine's borrowing costs spike and the currency lose nearly 10 percent of its value as frightened consumers rush to stock up on dollars and euros.

Several banks have reported hard currency shortages and the central bank on Friday was forced to impose capital controls and move the Ukrainian hryvnia's official rate to 8.7 from 7.9 per dollar -- its first shift of the peg since July 2012.

The simmering tensions in Kiev have also spilled over into verbal jousting between the European Union and Washington.

One leaked conversation that made a splash on Thursday showed Washington's European envoy Victoria Nuland using the f-word in a private conversation to disparage EU leaders' handling of the crisis, sparking strong condemnation from German Chancellor Angela Merkel.

But the US State Department has denied there is a rift between Washington and Brussels over Kiev, while admitting that the situation remained "complex".