Following a similar move last week that paralyzed the legislature for a few days, about 15 party members settled in the Supreme Rada in the morning to stop anyone approaching the rostrum or the presidential seat.
The pro-Russia party decided to take this course of action after the "orange" trio of the pro-presidential Our Ukraine bloc, the Yulia Tymoshenko Bloc and the Socialists had formed a coalition and agreed on nominees for the posts of prime minister and parliamentary speaker.
The Party of Regions gained the most seats in the Rada (186) after the March 26 elections, but was frozen out of negotiations between the three Western-leaning parties, which have an overall 243 seats.
Ukrainian parliamentarians also shunned Monday a roundtable initiated by the president to end the three months of political wrangling in the ex-Soviet republic.
President Viktor Yushchenko had put forward an idea to summon representatives of parties that made it into parliament in the March 26 elections but Communist leader Petro Symonenko was the only one to attend.
He left after waiting for his colleagues for 30 minutes and said the no-show signaled their lack of respect.
"Let them speak about their future participation in negotiations now," he said.
The Party of Regions, which is led by President Yushchenko's former rival in the 2004 presidential race Viktor Yanukovych, said it was too early to hold such a meeting.
If Ukraine's parliament fails to start work in the next three weeks, or fails to elect a prime minister and speaker, the president is entitled to dissolve it and call early elections.
