JERUSALEM — Amid police investigations and ethics probes enveloping Prime Minister Benjamin Netanyahu of Israel and his inner circle, a budding scandal over contracts for new submarines and other warships appears to be gaining momentum as another potential threat to his political future.

Police have been looking into Israeli contracts with a German shipbuilding company for the purchase of submarines and new missile ships that Netanyahu championed. His own lawyer, David Shimron, also represents the Israeli agent for the company, which has led to accusations of a conflict of interest in contracts that involve billions of dollars and the shape of Israel’s defense strategy.

Moshe Yaalon, whom Netanyahu ousted as defense minister last year and who opposed adding the new submarines, is reported to have recently given testimony. And Israel’s Supreme Court will hear a petition calling for the shipping affair to be the subject of a full criminal investigation. On Wednesday, Netanyahu filed a 45-page response, arguing the petition should be dismissed on grounds it had been brought by “publicity hungry’’ politicians.

Even as Netanyahu has made concessions to far-right politicians on the issue of West Bank settlements in recent weeks in a bid to retain his conservative constituency, some within his coalition see the pileup of cases involving the prime minister and his close associates as a political liability. A criminal indictment against him in any of them would most likely force him to resign.

Netanyahu, leader of the conservative Likud Party, in his third term in office, has vehemently denied wrongdoing.

It is unclear if Netanyahu is suspected of any personal misconduct.

One question is whether Netanyahu worked to cancel the bidding process for the missile ships. Asked about it in January, his office replied: “Prime Minister Netanyahu’s decision on this matter was based solely on the security of Israel and was recommended by Israel’s defense experts. It was also completely consistent with the law.’’

Days later, the office issued a statement that appeared to distance Netanyahu from the cancellation. The office attributed the decision to the Foreign Ministry, the Defense Ministry, and the navy.