KIEV, June 26 ??“ Ukraine??™s largest opposition group, the Regions Party, on Monday threatened to block operation of Parliament indefinitely unless the group gets control of key parliamentary committees and governments in regions it dominates.

In a statement, described by the group as an ???ultimatum,??? the Regions Party has also warned it may call on millions of voters to get to the streets unless the demands are met.

???We will not let Parliament leadership start any session,??? the party said. ???Parliament will not be able to debate any issue, will not be able to take any single move.???

The ultimatum is the most serious threat to undermine the work of the government since March 26, when the Regions, a moderate pro-Russian group, had won election by collecting most of votes.

It underscores the party??™s frustration with the creation of the pro-Western coalition in Parliament after its own talks with Our Ukraine, President Viktor Yushchenko??™s party, had failed to produce a coalition.

The Regions Party issued the statement after learning that the coalition members will probably appoint their loyalists to head all imports committees, such as committees on budget, organized crime and freedom of speech.

???These committees??¦ even under the previous regime [of President Leonid Kuchma] belonged to the opposition,??? the Regions Party said. ???We didn??™t seek to be in opposition, but now the ???orange ones??™ will learn what??™s the real opposition is like.???

The Regions Party, which controlled more than 70 seats in the previous Parliament, had been successfully blocking the appointment of judges to the Constitutional Court for five months. Now, the Regions control 186 lawmakers in 450-seat Parliament, a force that would be able to carry out the threat, analysts said.

The development shows frictions have been rising in relations between the pro-Western coalition, which controls 243 lawmakers, and the Regions, that may potentially put significant pressure on the government.

The clash may have repercussions on the country??™s politics as the Regions, which dominates eastern and southern regions, such as Donetsk, Luhansk and Crimea, may appeal to voters.

???Unless the ultimatum is fulfilled, we reserve the right to appeal to the people,??? the Regions said.

As a likely test showing the power of the Regions Party to mobilize the crowd, a trade union federation, effectively controlled by the party, has scheduled a massive protest rally in downtown Kiev on Tuesday. The rally is aimed at putting pressure on the government to cancel an 85% gas price hike scheduled on July 1.

Another demand in the ultimatum includes election of Parliamentary speaker by casting ballots as opposed to using an electronic voting system in Parliament.

By insisting on using the ballots, the Regions Party apparently hopes that not all lawmakers from the pro-Western camp would vote for Petro Poroshenko, Our Ukraine??™s most likely nomination, and that may undermine the coalition and force Our Ukraine to again start talks with the Regions, analysts said. (tl/ez)