KIEV, Sept. 3 – Tensions rose sharply in Ukraine on Monday after the Regions Party led by Prime Minister Viktor Yanukovych suddenly decided to join Parliament’s controversial emergency session on Tuesday, openly challenging President Viktor Yushchenko.

Yushchenko, who believes the government may use the session to try to cancel or to postpone the Sept. 30 election, in a strongly worded statement said these plans will “fail.” He directly blamed Yanukovych for the escalation.

“According to the constitution, Parliament of the fifth convocation is incapable,” Yushchenko said in a televised address to the nation late Monday. “Any decision approved by such Parliament is illegitimate, has neither practical force nor political effect.”

“Actions by people’s deputies that go beyond the law will get a clear legal assessment,” Yushchenko warned.

“I want this to be heard by everybody, first of all by Prime Minister and leader of the parliamentary coalition Viktor Yanukovych,” Yushchenko said. “The intention to hold the session of Parliament on Sept. 4 will fail.”

As a further sign of the escalation of political tensions, Yushchenko on Tuesday will hold a meeting of the country’s top security body, the National Security and Defense Council. The body may generate decisions that once signed by the president override decisions of the government.

The prime minister, as the member of the council, must be present at a meeting of the body, according to the constitution. But Yanukovych, in an apparent defiance, instead plans to visit the region of Luhansk on Tuesday with a routine trip.

The developments show that relations between the pro-Western president and the pro-Russian prime minister have worsened dramatically over the past 24 hours, and may turn into an open stand-off.

This comes as the prime minister has again changed his public position towards the emergency session of Parliament that highlights his maneuvering ahead of the Sept. 30 election.

On Sunday Yanukovych said his party would not attend the emergency session of Parliament if it “poses a threat of destabilization in the country.” However, on Monday the party decided to go ahead and to join the session despite a warning from Yushchenko.

Analysts said the flip-flop was probably caused by Yanukovych’s apparent failure to secure a promise from Yushchenko for joining forces of their parties after the election to form the next government.

This comes amid growing public support for two pro-Western groups, Yushchenko’s Our Ukraine-People’s Self-defense and the group led by former Prime Minister Yulia Tymoshenko.

As electoral support for the Regions Party and for its coalition partners, such as the Communist Party and the Socialist Party, has been either stagnant or falling, the pro-Western alliance would probably be able to unseat Yanukovych, opinion polls showed.

“Behind this provocation [of holding the session], there is a deep desire to cancel the election,” Yushchenko said. “It is caused by fears of losing the power and their personal seats in this power.”

Justice Minister Oleksandr Lavrynovych said last week that should 300 lawmakers show up for the emergency session in the 450-seat Parliament, this would automatically cancel the snap election.

A massive exodus of lawmakers from opposition groups and their joining the coalition was required for this scenario to materialize, analysts said. But there was no clear evidence that the coalition, which currently numbers 265 lawmakers, had managed to boost their ranks to 300 seats, analysts said. (tl/ez)