Israeli police officers on Thursday questioned Prime Minister Benjamin Netanyahu under caution for a second time this week on suspicion of taking gifts from businessmen in breach of his role as a public servant.
Police said the session, which lasted some five hours, was held at Netanyahu's official residence in Jerusalem. A first interrogation that took place on Monday lasted three hours.
In questioning a suspect under caution, police believe that the person they are interviewing has a case to answer.
"The investigation under caution of (Netanyahu's) alleged receipt of benefits continued today and involved questioning about another affair ... due to a fear of disrupting the investigation, no further details can be revealed at the moment," a police statement said.
It added that during the past two days, an additional suspect, who was not named, was also questioned.
Netanyahu has repeatedly denied any wrongdoing and has told his political rivals not to expect his imminent downfall.
"Wait with the celebrations, don't rush," Netanyahu told lawmakers in parliament earlier this week before questioning began . "I've said it before and I'll say it once again: there will be nothing because there is nothing."
The move to interview the Israeli leader was authorized by Attorney General Avichai Mandelblit, who decided after a preliminary inquiry that there was enough evidence to open a criminal investigation. He has not detailed the suspicions.
"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 said in a statement on Monday.
The left-wing Haaretz newspaper and other news outlets have said the probe relates to gifts worth "hundreds of thousands of shekels" ($1=3.85 shekels) given to Netanyahu by an Israeli and a foreign businessmen.
Channel 2, a commercial network, said the investigation was one of two cases now open against the prime minister, although it said details of the second remained unclear.
Netanyahu, 67, has been in power on and off since 1996. He is currently in his fourth term as prime minister and will become Israel's longest-serving leader if he stays in office until the end of next year.
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.
Netanyahu is not the first prime minister to be questioned in a criminal case and Israeli commentators have pointed out that although he is being questioned, as has happened many times before, prime ministers have continued to stay in their post, sometimes for years.
Ehud Olmert, who held office from 2006 to 2009, is currently serving 18 months in prison after being convicted of breach of trust and bribery in 2014.
Another former prime minister, the late Ariel Sharon, was questioned while in office in 2003 and 2004 over allegations of bribery and corruption involving him and his two sons. In 2006, his son Omri was convicted of corruption and served time in prison.