Supporters of former Ukrainian Prime Minister Yulia Tymoshenko clashed with police outside a Kiev appeals court on Tuesday.
The court is due to hear an appeal by Tymoshenko later in the day.
The ex-premier was jailed in October for seven years on abuse of office charges over a gas deal she concluded with Russia in 2009, a verdict internationally condemned as politically motivated.
The clashes broke out when her supporters attempted to storm the court. Police forced them back.
A number of members of parliament also clashed with security officers when they were denied admittance to the court building.
Tymoshenko was not brought to the court. Her lawyers earlier said she would be unable to attend for health reasons.
Since her conviction, prosecutors have reopened an investigation into tax evasion dating from the late 1990s, when Tymoshenko was head of Ukraine’s Unified Energy Systems.
