Tens of thousands of people gathered on the Ukrainian capital's Independence Square on Sunday, breathing new life into anti-government and pro-EU demonstrations that have tailed off during the past couple of weeks surrounding Orthodox Christmas and New Year, which falls on Tuesday.

"What are the next steps? We will fight... protest peacefully," Vitaly Klitschko a former world heavyweight boxing champion-turned opposition politician told the crowd. "Today the authorities use the militia as a weapon, silencing the people's mouths with batons," he said, in an apparent reference to a police crackdown on a much smaller demonstration early on Saturday.

At least 10 people were reported injured, including former Interior Minister Yuri Litsenko, when police moved in to break up a demonstration outside of a Kyiv courthouse.

Another opposition leader, Arseny Yatsenyuk, accused current Interior Minister Vitaly Zakharchenko of authorizing the use of force on demonstrators.

The public prosecutor's office said on Saturday that it had opened an investigation into allegations of abuse of power by police in connection with the incident.

This was the first time that force has been used against an opposition politician, but late last month, journalist Tetyana Chornovol had to be hospitalized after being beaten up by unknon assailants. She said she believed she had been attacked as revenge following her investigative work on President Yanukovych and other top officials.

No to EU deal

The recent wave of protests was sparked by a decision by President Viktor Yanukovych back in November not to sign an Association Agreement with the European Union, which would have increased political ties with the 28-member bloc.

Yanukovych later confirmed Kyiv's turn towards Moscow by signing a $15 billion (11 billion euros) bail-out package offered by his Russian counterpart, Vladimir Putin, who also slashed the price the former Soviet state pays for natural gas imports.

Sunday's demonstration was much smaller than the biggest rallies, which brought hundreds of thousands of people out onto the streets. There was no immediate estimate from police as to how many had turned out on Sunday, but news agencies put the figure at around 50,000.

pfd/dr (AP, Reuters, AFP)