Pro-Western Ukrainians started gathering for a fresh rally in the heart of Kiev on Sunday amid swelling anger over the bloody beating of prominent former minister turned opposition leader Yuriy Lutsenko.

The 49-year-old member of jailed ex-premier Yulia Tymoshenko's cabinet was transferred out of intensive care late Saturday after being attacked by truncheon-wielding police during a small protest the night before.

"He received about 10 blows to the head," the former interior minister's spokeswoman said.

Nearly 20 protesters were injured in all when they tried to prevent the police from moving to jail three activists who were sentenced to six years for allegedly plotting to blow up a statue of Soviet founder Lenin in 2011.

It marked the first use of force against a leader of Ukraine's latest wave of pro-Western protests and threatened to reignite the worst political crisis of President Viktor Yanukovych's four-year rule.

The ex-Soviet nation of 46 million that once served as the breadbasket of Europe has been rocked by ceaseless demonstrations ever since Yanukovych in November ditched an historic EU trade deal in favour of tighter ties with old master Russia.

The biggest rallies on Kiev's iconic Independence Square drew hundreds of thousands -- an echo of the 2004 Orange Revolution that first nudged Ukraine on a westward path. The heart of the city remains occupied by a tent city protected by makeshift barricades to this day.

Protest numbers began to recede when Yanukovych brushed aside the havoc in mid-December and struck a $15-billion (11-billion-euro) bailout package with Russia that also slashed the price Ukraine has to pay for natural gas imports on which its teetering economy depends.

The deal removed the immediate threat of a painful Ukrainian currency devaluation and debt default but also dimmed the prospects of a so-called Association Agreement being struck with the European Union in the coming months.

But top opposition leaders such as former boxing champ Vitali Klitschko -- another strong Tymoshenko supporter -- said the latest outburst of police violence showed the importance of a continued effort to topple Yanukovych's team.

"This once again shows that the protests on squares across the country must continue," said a Klitschko statement that was also signed by opposition leaders Arseniy Yatsenyuk and Oleg Tyagnybok.

"We will do everything to remove the authorities and change a system that allows the police to beat its people on crazy orders," the statement said.

The protest movement had lost much of its steam in the past two weeks because of a winter holiday season that stretches in post-Soviet countries from New Year's Eve to Orthodox Christmas -- celebrated according to the Julian Calendar on January 7.

The so-called "Old New Year" is also marked by many on January 14 and families often leave big cities or take vacations for the entire two-week stretch.

Sunday's protests were due to kick off at 1000 GMT. A few hundred had gathered under the Independence Monument towering over the city's central square -- known locally as the Maidan -- by Sunday morning.