Party leader Viktor Yanukovych said his party is prepared to continue blocking parliament for 30 days to prevent a new government being formed.
The parliament is now expected to reconvene on June 29.
The Party of Regions won the most votes in March parliamentary elections, but failed to win a majority. After three months of negotiations, the Our Ukraine bloc of President Viktor Yushchenko, the party of former Prime Minister Yuliya Tymoshenko, and the Socialists agreed last week to form a coalition.
(UNIAN, Interfax, AP)
The Key Players
BEHIND THE IMAGES: Click on the links below to read RFE/RL's profiles of some of the key players in Ukraine's March 26 legislative elections:
Click on the image to view a photo gallery of some of the key players in the Ukrainian elections.