MOSCOW (AP) _ In a victory for President Boris Yeltsin, Russia's Supreme Court ruled Tuesday that a criminal investigation into Prosecutor General Yuri Skuratov may go ahead, Russian news agencies reported.

The ruling was the latest twist in a bitter fight between Skuratov and Yeltsin that has included allegations of Kremlin corruption and the airing of a secret sex tape on national television.

Skuratov called the ruling ``biased and unfair'' and said he is ``not guilty of anything,'' according to the Interfax news agency. ``I didn't expect that the Supreme Court would come to such a decision,'' he was quoted as saying.

Yeltsin has tried to fire Skuratov for months. Parliament's upper house _ the only body that has the right to authorize the dismissal _ twice refused to do so.

The first refusal came after the airing of a tape that allegedly showed Skuratov having sex with two prostitutes. Yeltsin's enemies said the tape's release was a political dirty trick by the Kremlin.

The president succeeded in suspending Skuratov when a Moscow prosecutor launched an inquiry into allegations that criminal suspects provided Skuratov with prostitutes in exchange for dropping cases against them.

A lower court ruled the investigation was illegal and demanded that it be stopped. But the Supreme Court upheld an appeal of that ruling from Russia's military prosecutor, which had been leading the investigation.

Skuratov had been looking into alleged corruption among top Kremlin officials before the fight with Yeltsin began. Skuratov says the attempts to fire him were intended to block his inquiry.