was his party's first place finish in a parliamentary election and the right to head the ex-Soviet state's government. "We must now declare firmly that we are ready to defend our choice and that we will accept no revision of the election results," he said, after President Viktor Yushchenko ordered a probe into ballot counting in eastern and southern regions.
"We have won and I am confident that yet again we will be forming a government of people's trust, a government of national unity ... In line with all international standards the Regions Party has every right to form a government."
President Viktor Yushchenko, the prime minister's arch rival from the time of the "Orange Revolution" protests that thrust him to power in 2004, ordered an immediate investigation into delays in vote counting in the prime minister's strongholds.
"I am concerned by the delayed vote count in eastern and southern Ukraine," a sombre Yushchenko said in a televised address to the nation.
"I order law enforcement bodies to start an immediate investigation into the causes and circumstances of delayed vote count reports from polling stations."
Yushchenko did not mention any of his political adversaries by name, but warned that "those who commit fraud will be punished. Do not call into question the law and your own fate."
Rigging prompted the 2004 "orange" protests that overwhelmed Kiev for weeks in the aftermath of a presidential poll, initially won by Yanukovich. The supreme court annulled the vote and ordered a new poll won by Yushchenko.
