JERUSALEM - Police questioned Prime Minister Ehud Olmert on Friday in an investigation of campaign donations by a U.S. citizen. It is the fifth high-profile probe involving the Israeli leader whose popularity has badly suffered because of repeated charges of corruption.

Olmert's office predicted he would weather the latest storm, but it threatened to further weaken his hold on power and potentially derail peace talks with Palestinians.

With a court-imposed gag order limiting information about the investigation, it isn't clear what allegations police are looking into, but Israeli law restricts how much politicians can get from donors.

Olmert was questioned under caution, indicating police thought their interrogation could result in an indictment. If Olmert was indicted, he would have to resign. A decision on formal charges was at least months away.