Mr Olmert denies wrongdoing in the three investigations

The trade and industry ministry and the headquarters of the national post office were among the places searched.

The prime minister is the subject of three criminal investigations - but denies any wrongdoing.

The inquiries involve the purchase of a property, a bank privatisation deal, and alleged political favours when he was trade and industry minister.

More than 100 police officers were involved in the raids just after dawn on Sunday.

OLMERT TIMELINE 1945: Born in Binyamina 1973: Elected to the Knesset 1993-2003: Jerusalem mayor 2003-2006: Ministerial posts April 2006: Prime minister

Profile: Ehud Olmert

Police spokesman Mickey Rosenfeld said: "Police investigators are searching a number of government and private offices in connection with three ongoing investigations."

He said police were expected to confiscate documents and other materials.

The investigations against Mr Olmert are into:

Allegations of appointing political allies to positions throughout the trade and industry ministry when he headed it between 2003 and 2005

Allegations he tried to influence the sale of the state's controlling interest of Bank Leumi in favour of a friend in 2005

The purchase of a house in Jerusalem which a government watchdog concluded was sold below market value by a developer.

Mr Olmert has strenuously denied any wrongdoing and has insisted that the investigations are part of a political vendetta against him.

BBC Middle East correspondent Tim Franks says Mr Olmert's position seems safe for the time being.

Our correspondent says that even if the prime minister were indicted he would not necessarily be forced to step down and, at the moment, his coalition government appears firm.