The United States said Tuesday there is no reason to believe that results of Ukraine's December 26 presidential election re-vote will be overturned.  But it is nonetheless withholding congratulations for President-elect Viktor Yuschenko.

The Bush administration is taking a cautious approach as the Ukrainian election process nears an end, in part because it was critical of Russia's early embrace of Viktor Yanukovych as winner of the run-off election in November that was annulled by the country's supreme court.

Ukraine's Central Election Commission late Monday announced final results of the December re-run, saying opposition leader Viktor Yuschenko won with 52 per cent of the vote.

But the Supreme Court halted publication of the results, saying it must first hear a final appeal from Mr. Yanukovych, the former prime minister, who has refused to concede defeat.

At a news briefing, State Department Spokesman Richard Boucher welcomed the certification by the election commission as a "momentous step" in the Ukrainian people's struggle for democracy.

However, he said the United States doesn't plan to congratulate a winner until all legal challenges have been resolved and the final results published:

"I think most observers, both Ukrainian and international observers, have concluded there were no systemic violations, and that any violations that did occur did not affect the outcome of the December 26th vote,” he said.  “Ukrainian law does provide an avenue for challenges, and so we'll let that process play itself out. We certainly are confident that the Supreme Court will deal with the matter, promptly, fairly and in a transparent manner."

Mr. Boucher said he did not want to speculate on who would represent the United States at inauguration ceremonies in Kiev, expected to occur within a matter of days.

He said the electoral process in Ukraine has been a matter of great importance to Secretary of State Colin Powell, and to President Bush as well.

Mr. Powell is expected to step down as soon as the end of next week, after the all-but-certain Senate confirmation of Condoleezza Rice as his successor.

On a related matter, Spokesman Boucher said the United States "trusts" that changes in Ukraine's troop commitment in Iraq in will be made in a responsible and measured way, and in full consultation with the Iraqi government and other coalition partners.

Outgoing Ukrainian President Leonid Kuchma Monday told the country's defense and foreign ministries to draw up plans for the withdrawal of the 1650 member contingent within six months.

The country's parliament also approved a non-binding resolution calling for a troop withdrawal. Eight Ukrainian soldiers were killed in an explosion at an Iraqi ammunition dump last weekend, bring to 16 the total number of Ukrainians who have died there.

Mr. Boucher said Ukraine has been a "very important partner" in Iraq and that the United States is grateful for its contribution. He said U.S. officials are aware that Mr. Yuschenko campaigned for an end to the Iraq troop presence, and said they expect to discuss the matter with the new government in Kiev when it chooses to bring it up.