The questioning is part of a criminal investigation ordered by Menahem Mazuz, the attorney general, in January.
Series of scandals
Olmert's popularity has plummeted following last year's inconclusive Lebanon war and a series of corruption scandals involving senior government officials.
Two weeks ago Mazuz ordered another criminal investigation of Olmert over his purchase of a Jerusalem home.
The Israeli leader is suspected of having received an effective bribe when he bought the property for an estimated 300,000 dollars below market price.
He has denied the charge.
Moshe Katsav, the former president, agreed a plea bargain deal earlier this year to avoid rape charges.
Haim Ramon, an ally of Olmert's, stepped down as justice minister after being convicted of sexual harassment.
Another investigation into alleged widespread corruption in Israel's tax authority forced the resignation of Olmert's personal secretary and close aide of 30 years, Shula Zaken.
Avraham Hirshson, a former finance minister resigned from his post in early July amid a police investigation over claims that millions of dollars were embezzled from a union he once headed.