Police have questioned Prime Minister Benjamin Netanyahu for three hours under caution at his official residence in Jerusalem on suspicion of receiving gifts from businessmen in breach of his role as a public servant.
Channel 10 TV has reported that Netanyahu's oldest son, Yair, accepted free trips and other gifts from Australian billionaire James Packer.
Part of a police statement issued after the questioning ended on Monday said that "investigators questioned PM Benjamin Netanyahu under caution on suspicion of receiving benefits."
In questioning a suspect under caution, police investigators believe that the person they are interviewing has a case to answer.
The move to question the Israeli leader was authorised by Attorney-General Avichai Mandelblit, who decided after a preliminary inquiry that there was enough evidence to open a criminal investigation.
Mandelblit issued a long statement which did not detail the matters being investigated but said the information warranted questioning under caution.
It also mentioned other suspicions which had been checked but did not yield evidence to warrant additional criminal inquiries.
"The nature of the investigation precludes us at this stage from giving details of the ongoing investigation but we will consider releasing more information from time to time according to developments," Mandelblit's statement said.
He added that investigations began three months ago but new, detailed information had come to light during the past month which supported questioning the prime minister under caution.
Before the questioning began, Netanyahu told his ruling Likud faction in parliament that those anticipating his downfall should not expect his imminent departure.
"Wait with the celebrations, don't rush," Netanyahu said. "I've said it before and I'll say it once again: there will be nothing because there is nothing."
Photographers were camped outside the heavily guarded residence, hoping to get pictures of investigators arriving. Black screens were erected inside the gates of the property to block the view.
Haaretz and other newspapers said the probe related to gifts worth "hundreds of thousands of shekels" given to Netanyahu by Israeli and foreign businessmen.
Netanyahu, 67, has been in power on and off since 1996. He and his wife, Sara, have weathered several scandals over the years, including investigations into the misuse of state funds and an audit of the family's spending on everything from laundry to ice cream. They have denied any wrongdoing.
