Ukraine's Prime Minister Viktor Yanukovich said Saturday he will contest the presidency in a new runoff vote on Dec. 26 against the opposition leader Viktor Yushchenko.

Ukraine's Supreme Court on Friday annulled the official result of last month's runoff, stripping the prime minister of his victory. After assessing the opposition claims that the Nov. 21 vote was rigged in favor of Yanukovich, it ruled that a revote must be held on Dec. 26.

"I am certain that the supreme court's decision is a violation of the Ukrainian constitution and that it was taken under pressure from the street," Yanukovich said in a statement Saturday.

"Without any doubt, I have no other choice but to run again andto win," he said.

Earlier, Yanukovich's spokeswoman Anna German said he will participate in the repeat vote as he is confident he will win.

Ukraine's parliament was meeting Saturday to pass laws needed to hold a rerun of a presidential runoff election. Lawmakers were also expected to demand that President Leonid Kuchma sack Yanukovich and appoint a new cabinet.

The parliament passed a no-confidence vote on Yanukovich Thursday.

Yanukovich and Yushchenko each won around 40 percent of the vote in the first round of the presidential election held on Oct. 31. The Central Election Commission declared Yanukovich the winner of a runoff vote on Nov. 21, which was protested by the opposition and sparked turmoil in major cities in the country.

Yanukovich enjoys strong backing in the heavily industrialized eastern half of the country, while Yushchenko draws much support from Ukraine's west, a traditional stronghold of nationalism.