KIEV, May 8 – President Viktor Yushchenko’s Our Ukraine group issued a warning Thursday that Ukraine’s governing coalition will come under major stress if Prime Minister Yulia Tymoshenko moves to amend the constitution by reducing presidential powers.

On the other hand, Yushchenko’s office has been quietly working with the Regions Party, the biggest opposition group, seeking to avert the approval of the amendments, people familiar with the situation said.

The developments come a day after Tymoshenko had announced plans to submit the amendments for debate and approval by Parliament next week, underscoring her increasing rivalry with Yushchenko.

“This is a serious matter to be hastily approved by Parliament,” Viacheslav Kyrylenko, the leader of Our Ukraine, said Thursday. “If we want to amend the constitution for the better, the amendments must be worked out by the best experts in the field of law, civil leaders, local communities and this process must be maximum transparent.”

Kyrylenko warned that approval from Our Ukraine, Tymoshenko’s coalition partner, was crucial for the fate of the bill and the future of the coalition.

“If the Tymoshenko group seeks to submit the amendments, according to a coalition agreement, they first must be approved by a consensus vote of the coalition council,” Kyrylenko said.

Meanwhile, the Yushchenko office has been quietly talking to the Regions Party to avert the amendments, the people said.

The Tymoshenko group and the Regions Party have enough votes to override a veto from the president, which explains on-going consultations between Yushchenko and the Regions.

The Yushchenko office has been apparently seeking to capitalize on an recent attack by the Tymoshenko government on the acquisition of a stake in DniproEnergo, a major fossil-burning power producer, by Rinat Akhmetov, a key financial sponsor of the Regions Party.

Tymoshenko recently reversed a previous government resolution that had allowed Akhmetov to increase the stake in the power company through debts-for-assets arrangement.

Yushchenko increased personal contacts with Akhmetov over the past several weeks, visiting Donetsk and most recently attending a soccer game in Kharkiv at which Akhmetov’s Shakhtar Donetsk had defeated Dynamo Kyiv. (tl/ez)