Ukrainian Prime Minister Viktor Yanukovych says he will challenge Sunday's presidential election results in the Supreme Court, charging thousands of violations.
With nearly every vote counted, opposition candidate Viktor Yushchenko leads Mr. Yanukovych 52 to 44 percent.
Mr. Yanukovych says he will not recognize the results, saying human rights and the constitution were violated.
He pointed to election reform laws that he says favored his opponent.
Ukrainian election officials have not commented. But a spokesman for European election monitors says Sunday's vote brought Ukraine much closer to meeting international standards for a free and fair election.
Ukraine's Supreme Court ordered Sunday's re-vote after it threw out the November 21 presidential election, won by Mr. Yanukovych, because of massive fraud.
Some information for this report provided by AFP, AP.