JERUSALEM (Reuters) - Israeli Prime Minister Benjamin Netanyahu alleged on Wednesday that Iran could blackmail his main election rival, Benny Gantz, after hacking the former armed forces chief’s phone, even as Tehran denied doing so.

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Without providing any evidence or details, Netanyahu said Iran had gleaned “sensitive information”. His comments, in a brief speech broadcast online from his official residence, brought a new level of vitriol to the election race.

Polls put Netanyahu’s right-wing Likud and Gantz’s centrist Blue and White party neck-and-neck, with election day three weeks away.

Gantz has confirmed an Israeli TV report last week that the Shin Bet domestic intelligence service had detected that his cellphone had been hacked, though the agency itself has not commented.

But he has not confirmed that the hackers are believed to be Iranian, as reported, and has said the phone contained no data that might compromise national security or his ability to carry out his duties if he were elected prime minister.

Iran denied that its intelligence services had hacked Gantz’s phone.

“The (Israeli) regime’s officials are long used to spreading lies,” Foreign Ministry spokesman Bahram Qasemi said, according to the state news agency IRNA.

Gantz, for his part, has sought to focus public attention on the state’s decision not to deem Netanyahu a suspect in a graft scandal over a German submarine deal. Netanyahu, who denies wrongdoing, faces possible indictment in three other corruption cases.

Netanyahu said there was more to be revealed about the contents of the ex-general’s mobile phone.

“What do the Iranians know about you that you are hiding from us?” Netanyahu said. “And above all else, how would you, as prime minister, face up to Iran, our number one enemy, when Iran has sensitive information about you? This is not a matter of gossip. This is a matter of national security.”

Netanyahu called on Gantz to come clean as “the only way not to be vulnerable to blackmail”.

Speaking to the Israeli News Company TV station on Tuesday, Gantz said the Shin Bet had informed him six months ago that “there was a small problem - and I am taking care of it”.

“I have a wonderful family. I have wonderful children. My wife supports me from here until further notice,” he said.

Asked if there was anything on the phone that could be used for blackmail, Gantz said: “Nothing can have an influence over my performance.”