Jerusalem - Israel's anti-corruption unit has said Prime Minister Ehud Olmert's announcement that he will step down in September will not affect the ongoing corruption probe against him, Israeli media reported Thursday.

Police detectives probing a string of corruption allegations against Olmert are due to question him again on Friday over some of them.

"The investigation continues as normal. Detectives will question Olmert on Friday at his residence irrespective," a spokeswoman for the National Fraud Unit was quoted as saying in the Jerusalem Post daily.

The allegations against Olmert involve suspicious money and property transactions and investments and deals involving friends that span more than a decade.

Olmert denies any wrongdoing and when announcing his intention to to quit the premiership, said Wednesday night that "as prime minister, I have been denied the basic right to the presumption of innocence."

"Police have so much material relating to Olmert that it gives you a headache to look at it," former fraud unit head Boaz Guttman told the newspaper. "Right now there is enough material for a sure conviction of fraud and violation of public trust."

On Friday, Olmert is expected to answer to investigators who suspect he frequently billed various public agencies for expenses related to single trips and pocketed the surplus.

Investigators have questioned him on three previous occasions since May on suspicions that he illictly took tens of thousands of US dollars from a Jewish American businessman and fundraiser. (dpa)