The Blue and White party on Friday called for Prime Minister Benjamin Netanyahu to immediately resign as a government minister due to the decision by Attorney General Avichai Mandelblit to indict him for fraud, bribery and breach of trust.
Lawyers for the party issued the call to the prime minister and the attorney general.
Netanyahu is being charged in three separate cases, known as Case 1000, Case 2000 and Case 4000. A separate investigation, known as Case 3000, was closed for the prime minister.
"According to a Supreme Court's decision... a minister who is indicted cannot continue to hold office, and therefore it is imperative that you immediately terminate your various positions as minister in the Israeli government," Blue and White said.
The Supreme Court decision refers to a statement that a government official indicted on serious charges must be removed from office if they do not resign of their own accord.
Aside from his position as prime minister, Netanyahu serves as health minister, welfare minister, Diaspora affairs minister and acting agriculture minister.
Blue and White said: "Without at this time questioning your ability to serve as prime minister in light of the attorney general's announcement, you have a clear obligation that cannot be interpreted in any other way, given (the previous) judgments… to immediately resign from all the ministerial positions in which you serve."
The party added, "it is incumbent on the attorney general to instruct Mr. Netanyahu to resign from his additional positions immediately."
Blue and White also warned that if Netanyahu did not resign from these positions, " our representatives will be forced to take all measures open to them, including a petition to the High Court."
Netanyahu did win some further support from his own party Friday, with Foreign Minister Israel Katz saying there was no legal reason for him to step down as prime minister.
"I support Prime Minister Netanyahu and strengthens his hand at this difficult time," Katz said.
"Israel is a nation of laws and everybody is granted the presumption of innocence," he said.
"As long as there are no legal disqualifications to Netanyahu's tenure as prime minister he may continue in office."