Ten people were injured and at least 50 arrested in Kiev on Saturday following clashes between police and anti-corruption protesters who have set up camp outside the Ukrainian parliament.
Dozens of supporters of Mikheil Saakashvili, the former leader of Georgia and one-time governor of Ukraine's Odessa region, erected their tents in October and have been holding regular rallies demanding the resignation of President Petro Poroshenko.
"Six protesters sought medical assistance, four police officers were wounded" as a result of the clashes, Kiev police chief Andriy Kryshchenko told the Ukrainian 112 TV channel.
Fifty people were detained as they resisted police troops, he added.
Kryshchenko said police raided the tents as a part of an investigation after protesters tried to seize a building in Kiev's city centre at the end of last year.
Saakashvili was once an ally of Poroshenko, but then became one of his greatest foes.
Kiev accuses the 50-year-old of trying to stage a coup sponsored by allies of former Kremlin-backed Ukrainian president Viktor Yanukovych -- a charge he strongly denies.
In February Saakashvili, who had been living in exile in Ukraine, was detained by security officers in Kiev and deported to Poland.
Later in the month he was banned from entering Ukraine for three years.
A court last year found Saakashvili guilty of illegally crossing Ukraine's border after he forced his way back into the conflict-riven country with the help of hundreds of supporters, pushing aside border guards.
Ukraine stripped him of his citizenship in 2016, rendering him stateless as he had already lost his Georgian citizenship.