Scuffles have broken out in the Georgian capital Tbilisi as protesters sought to stop President Mikheil Saakashvili from delivering a speech.
Politicians loyal to the president, including MPs and the mayor of Tbilisi, were assaulted outside the national library, where he was due to speak.
Mr Saakashvili, who chose the library after being prevented from speaking in parliament, had to abandon the attempt.
His office said he would try to speak from the presidency instead.
The protesters accuse Mr Saakashvili, whose party lost last year's general election to a bloc led by Bidzina Ivanishvili, of flouting human rights and stifling dissent.
Mr Ivanishvili, now prime minister, said earlier this week that he would boycott Mr Saakashvili's annual state-of-the-nation speech, accusing him of lying.
Members of the government want the president to agree to constitutional changes, which would strip him of the power to sack the government, the BBC's Damien McGuinness reports from Tbilisi.
The pro-Western president must by law step down in October.