The allegations against Olmert are under a gag order but are believed to involve bribery, The New York Times reported Monday.

U.S. Secretary of State Condoleezza Rice is in the Middle East to try to advance peace negotiations between Israelis and Palestinians.

Israeli Channel 2 News reported Sunday that Olmert's aide, Shula Zaken, was questioned for a third time and quoted "senior sources" as saying indictments may be close to being issued, the Times said.

During his weekly Cabinet meeting, Olmert tried to blunt the rumors of the investigation.

"To my regret, for reasons that do not depend on me, the country has been swept with a wave of rumors regarding the investigation," Olmert's spokesman reported the prime minister as saying. "I am certain that when matters are made clear, with the permission of the proper authorities, matters will be presented in the correct proportion, in their right and exact context and that this will put an end to the rumors."