Activists of pro-democracy youth organization Pora, which is pushing for the dissolution of Ukraine's legislature, became involved in a skirmish with members of Unity movement who tried to remove the rival party's tent camp from Kiev's main square, the site of major government buildings.
Police stepped in to stop the clash.
Pora was a proactive participant in Ukraine's 2004 mass protests against vote rigging that swept into power pro-Western opposition leader Viktor Yushchenko.
Tents have reappeared in central Kiev as many Ukrainians, frustrated over a parliamentary deadlock that has lasted since March, have taken to the streets to protest against a coalition of leftist parties blocking the legislature's work. Although reminiscent of the 2004 rallies, which became known as the "orange revolution," the current protests are a far cry in numerical terms.
Yushchenko has dismissed as illegitimate the new coalition, forged last week by Viktor Yanukovych's Party of Regions with the Communist Party and the Socialists, and refused to accept the nomination of his presidential rival as prime minister.
Yushchenko can now either conclude a power-sharing deal with Yanukovych or dismiss the legislature and call an early election.
In a radio address Saturday, he said not all possibilities to overcome the parliament impasse had been exhausted yet, but warned that a solution should be found before July 25.
In keeping with the constitution, the president will have to dissolve the assembly unless it forms a coalition government by that date.
