Israel’s defense minister on Sunday appointed a committee to investigate the government's controversial purchase of German submarines several years ago, a step that further strained his already poor relationship with Prime Minister Benjamin Netanyahu.

The $2 billion purchase of the submarines and warships made by Thyssenkrupp is the focus of a sweeping corruption scandal in which seven businessmen, including confidants of Netanyahu, have been named as suspects.

Netanyahu, who is on trial for his involvement in three other corruption scandals, is not a suspect in the submarine case but critics, including his defense minister at the time of the purchase in 2015, have said Netanyahu behaved improperly and may have had a conflict of interest.

Defense Minister Benny Gantz, who is Netanyahu’s main coalition partner, said he had decided to appoint the committee after weeks of consultations with legal and defense officials. He said the committee, to be headed by a retired judge, would release its findings within four months.

Gantz and Netanyahu formed a power-sharing deal in May after battling to a deadlock in three consecutive elections but their government, ostensibly aimed at confronting the coronavirus crisis, has been plagued by infighting and paralysis.

If the rivals cannot reach a budget deal by Dec. 23, the country could be forced into another election next spring, right around the time the investigative committee is set to release its findings.

Netanyahu’s Likud party accused Gantz of acting out of political considerations, saying he is "scouring for votes" at a time when his Blue and White party is plunging in opinion polls.