Israel's former prime minister Ehud Olmert has officially been charged with corruption, relating to events before he became premier.

A year ago, Olmert was hoping to leave his mark as the man who achieved peace with the Palestinians. But these charges are multiple and serious and include allegations of taking cash-filled envelopes and double-billing for trips abroad. He has always insisted he is innocent.

The charges have been a long time coming. Olmert was dogged by corruption allegations throughout his time as prime minister.

But when he finally declared he would step down he fully expected he would eventually be cleared.

"I will vacate my seat in the proper way, respectfully, fairly and responsibly, as I have behaved throughout my term, and then I will prove my innocence and that my hands are clean," Olmert said last year.

But he will not appear so clean though if the charges are upheld, and could face at least five years in jail if he is found guilty.

Olmert is accused of accepting envelopes filled with cash from an American businessman, Morris Talansky.

In a police interview later played in court, Mr Talansky said he had handed Olmert $US25,000, only to be asked for more.

"He asked me for double the amount ... what do you think my name is, Rockefeller?" he said.

Olmert denies he has ever taken a single shekel that was not his, and has vowed to fight the charges in court.

He might have hoped his legacy would be as the Israeli leader who finally brought peace with the Palestinians. Instead, if he is found guilty, he might be remembered as a fraudster.

The chief political reporter at the Jerusalem Post, Gil Hoffman, says Olmert wanted to fall on the sword of peace but he is falling on the sword of corruption instead.

"That's what brought him down politically," he said.

"That's what forced the election that led to [Benjamin] Netanyahu coming to power. And it's very unfortunate for him because he really made an effort to move the peace process forward."

Corruption allegations are hardly new in Israeli politics, although Olmert could be the first former prime minister sent to jail.

Just recently two other former ministers were found guilty of corruption and sentenced to jail and the government that replaced Olmert's is itself tainted by allegations.

Just this month police formally recommended charges against Foreign Minister Avigdor Lieberman for graft and money laundering.

He too denies he has done anything wrong. A former president, Moshe Katsav, is currently on trial for rape.