A former Turkish prime minister appeared in an Ankara court Wednesday to face corruption charges. Former Prime Minister Mesut Yilmaz is the latest in a string of high ranking state officials being probed as Turkey seeks to stamp out corruption.

Radiating confidence, Mr. Yilmaz, who served three times as prime minister of Turkey, denied charges that he had helped to rig the privatization of a state-owned bank in order to enrich his business cronies. He also denied any contact with a notorious Turkish mafia boss said to be involved in the deal.

Mr. Yilmaz, whose center-right Motherland Party shared power on and off for two decades, is the first prime minister ever to be tried in a Turkish court. His trial is being viewed as evidence that Prime Minister Recep Tayyip Erdogan is determined to fulfill pre-election pledges to wipe out endemic corruption. The pledges helped propel Mr. Erdogan's conservative Justice and Development Party to power two years ago.

Yet Mr. Erdogan has found his own government assailed by allegations of corruption following the arrests earlier this week of two energy ministry officials. They are accused of unlawfully accumulating wealth through state tenders. The officials were appointed by Mr. Erdogan despite stiff resistance from Turkey's pro-secular president, Ahmet Necdet Sezer. Mr. Sezer has unsuccessfully sought to block the appointments of several other government officials thought to be either pro-Islamist or tainted by corruption.

Mr. Erdogan, who until recently embraced political Islam himself, faced harsh criticism last month when he and his wife accepted an expensive diamond necklace from a Turkish businessman in Moscow. He has also been condemned for failing to lift immunity for parliamentarians. Before coming to power, he had promised to lift the immunity privilege, which shields members of parliament from prosecution.

Recent opinion polls show that Mr. Erdogan continues to be supported by a firm majority of Turks. Analysts warn, however, that if the prime minister fails to tackle corruption among his own ranks, his party could end up like Mr. Yilmaz' Motherland Party, deeply unpopular and out of power.