Several opposition MPs in Ukraine were injured on Thursday evening in a brawl in parliament with ruling party MPs.
Supporters of opposition leader, former prime minister Yulia Tymoshenko, are now demanding a criminal inquiry into the incident.
Some MPs were admitted to hospital. Reports said some had fractures.
A corruption inquiry against Mrs Tymoshenko opened this week. The BBC reports Mrs Tymoshenko is accused of misusing public funds. She has been told not to leave the capital, Kiev.
Mrs Tymoshenko, who lost power in March, said the inquiry was politically motivated.