JERUSALEM — Prime Minister Benjamin Netanyahu of Israel has lashed out at the country’s police chief, whom he accused of airing “delusional and mendacious” insinuations against him, just days before the police are expected to publish recommendations regarding potential charges against Mr. Netanyahu in two corruption investigations, possibly including bribery.

“Any fair-minded person will ask themselves how people who say such delusional things about the prime minister can investigate him objectively and make recommendations in his case without bias,” Mr. Netanyahu wrote in a Facebook post after midnight Wednesday.

“A large shadow has been cast this evening over the police investigations and recommendations in the case of Prime Minister Netanyahu,” he added.

Critics said Mr. Netanyahu, now in his third consecutive term in office, was trying to discredit the police in order to delegitimize investigations that could undermine his political future.