An Israeli good governance group on Sunday asked the country's Supreme Court to punish Prime Minister Benjamin Netanyahu for allegedly violating a conflict of interest agreement meant to prevent him from dealing with the country's judiciary while he is on trial for corruption.

The request by the Movement for Quality Government in Israel intensifies a brewing showdown between Netanyahu's government and the judiciary, which it is trying to overhaul in a contentious plan that has sparked widespread opposition.

The Movement for Quality Government in Israel, a fierce opponent of the overhaul, asked the court to force Netanyahu to obey the law and sanction him either with a fine or prison time for not doing so, saying he was not above the law.

“A prime minister who doesn't obey the court and the provisions of the law is privileged and an anarchist,” said Eliad Shraga, the head of the group, echoing language used by Netanyahu and his allies against protesting opponents of the overhaul.

“The prime minister will be forced to bow his head before the law and comply with the provisions of the law.”

Netanyahu is barred by the country's attorney general from dealing with his government's plan to overhaul the judiciary, based on a conflict of interest agreement he is bound to, and which the Supreme Court acknowledged in a ruling over Netanyahu's fitness to serve while on trial for corruption.

But on Thursday, after parliament passed a law making it harder to remove a sitting prime minister, Netanyahu said he was unshackled by the attorney general's decision and vowed to wade into the crisis and “mend the rift” in the nation.

That declaration prompted the attorney general, Gali Baharav-Miara, to warn that Netanyahu was breaking his conflict of interest agreement by entering the fray.

The fast-paced legal and political developments have catapulted Israel into uncharted territory and to a burgeoning constitutional crisis, said Guy Lurie, a research fellow at the Israel Democracy Institute, a Jerusalem think tank.

“We are at the start of a constitutional crisis in the sense that there is a disagreement over the source of authority and legitimacy of different governing bodies,” he said.

If Netanyahu continues to intervene in the overhaul as he promised, Baharav-Miara could launch an investigation into whether he violated the conflict of interest agreement, which could lead to additional charges against him, Lurie said.

He added that the uncertainty of the events made him unsure of how they were likely to unfold.

It is also unclear how the court, which is at the centre of the divide surrounding the overhaul, will treat the request to sanction Netanyahu.

Netanyahu is on trial for charges of fraud, breach of trust and accepting bribes in three separate affairs involving wealthy associates and powerful media moguls.

He denies wrongdoing and dismisses critics who say he will try to seek an escape route from the charges through the legal overhaul.

The overhaul will give the government control over who becomes a judge and limit judicial review over government decisions and legislation.?

Netanyahu and his allies say the plan will restore a balance between the judicial and executive branches and rein in what they see as an interventionist court with liberal sympathies.

Critics say the plan upends Israel's fragile system of checks and balances and pushes Israel down a path toward autocracy.

The government has pledged to pass a key part of the overhaul this week before parliament takes a month recess, but pressure has been building on Netanyahu to suspend the plan.