At least ten people, including a former interior minister, were injured in the early hours of Saturday morning in clashes between riot police and protesters outside a courthouse in Ukraine's capital Kiev, witnesses said.
In the first clashes since last month, police using tear gas and batons tried to disperse a couple of hundred people protesting against three activists being sentenced to six years in jail, a case seen by protesters as politically motivated.
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About 10 km (6 miles) away, several thousand people have set up camp in central Kiev to protest against President Viktor Yanukovich's decision to abandon the trade agreement with Europe in favor of closer cooperation with Russia.
Protests began in late November and increased significantly in early December after riot police violently broke up a student demonstration in Kiev's main square.
Yuri Lutsenko, a minister in the government of jailed opposition leader Yulia Tymoshenko, was among the injured protesters. Lutsenko, pardoned last year by Yanukovich, was hit in the head, witnesses said.
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The police said in a statement they had no information about anyone being injured.