KIEV - Ukrainian President Viktor Yushchenko on Monday tapped top ally Yulia Tymoshenko to be prime minister in an appointment that pays tribute to her key role in his torturous election victory but also will likely vex his opponents at home and in Russia.

Yushchenko's office announced the decision while the president was in Moscow on his first foreign trip following his inauguration a day earlier. The visit was intended to smooth relations with Russia, Ukraine's powerful neighbor that had staunchly backed Yushchenko's rival for the presidency.

"Tymoshenko, of all the candidates that were proposed, was the most acceptable," Yushchenko said after a meeting at the Kremlin with President Vladimir Putin. "I hope that Yulia and her Cabinet will be successful."

However, Tymoshenko's nomination is likely to upset many in Russia, where prosecutors have issued an international arrest warrant for her on corruption charges dating back to her days as head of Ukraine's gas monopoly -- a company which has since been reorganized.

Tymoshenko, a firebrand opposition leader who occasionally wears leather jackets in parliament, was a driving force behind the opposition protests that paved the way for Yushchenko's victory in the Dec. 26 revote.

Earlier this month, Tymoshenko said a written coalition agreement between Yushchenko's Our Ukraine party and an opposition bloc that bears her name had promised her the prime minister's job.

Yushchenko's choice for prime minister will also sow fears among the part of Ukraine's business elite that was closely connected to the previous government.

"Especially in the first months it will be a tough and offensive style of leadership that can affect some business elites and their interests," said Oleksandr Dergachev, an analyst with the Kiev-based Institute of Political and Ethnic Studies.

Many observers expected Yushchenko to give the prime minister's job to one of his more moderate allies to avoid further polarizing society.

Tymoshenko has been widely popular among opposition supporters but detested by Yushchenko's foes in the mostly Russian-speaking east of the country, where she was born in the city of Dnipropetrovsk in 1960. She studied economics and cybernetics and earned a higher degree in economics. She has written more than 50 research papers.

Tymoshenko was deputy prime minister overseeing energy in 2000 and won praise for her efforts to reform the sector. Kuchma fired her after she was charged with forgery and smuggling gas in 2001. The case was linked to her activities with the gas monopoly in the mid-1990s, and she has dismissed it as a witch-hunt.

After spending a month in custody, Tymoshenko was cleared by a court, although prosecutors continued to investigate her, her husband and her father-in-law.