Conscription of ultra-Orthodox men has long been a divisive issue in Israeli politics, precipitating a protracted crisis that saw five parliamentary elections in under four years.

Ultra-Orthodox men are facing the possibility of being called up from April 1, as Israel's war against Hamas militants rages in the Gaza Strip.

But Netanyahu, who has depended on the support of ultra-Orthodox parties in successive coalition governments, asked the Supreme Court to delay a deadline for coming up with a conscription proposal.

He sought on Thursday a 30-day delay to allow more time to come up with an agreement with his ultra-Orthodox coalition partners, who are fiercely opposed to conscription for their community.

Attorney General Gali Baharav-Miara argued against a delay, telling the court that conscription needs to begin by April 1.

The court issued an interim ruling Thursday saying that Jewish seminaries would lose funding if students without deferrals or exemptions did not report for military service.

A hearing will be scheduled for sometime in May to hear arguments against making the order final, the court ruled.

Netanyahu ally Aryeh Deri called the ruling "a mark of Cain and unprecedented cruelty" for seminary students.

As tens of thousands of reservists have been called up for the war in Gaza, pressure has increased on the country's large and growing ultra-Orthodox community who have long been exempt from military service even though it is compulsory for nearly all other Jewish men in Israel.

Netanyahu is working to avoid an early election that might benefit Benny Gantz, a centrist member of his war cabinet, Yohanan Plesner, president of the Israel Democracy Institute think tank, has said.

Recent polls suggest that if there were an election, Gantz's party would win the largest number of seats.

Before the war, the religious parties had supported Netanyahu's controversial judicial reforms, in the hope of further extending military exemptions.

The judicial revamp sparked months of protests, often by tens of thousands of Israelis.

- Exemptions date back decades -

But Defence Minister Yoav Gallant in February announced a reform of military service that would include the ultra-Orthodox.

Some Israeli media perceived Gallant's move as a challenge to Netanyahu. Both men belong to the same Likud party.

Military service is obligatory for young Israelis -- 32 months for men, and two years for women.

But almost all the ultra-Orthodox have been able to escape it, with 66,000 members of the community excused from military service last year alone.

Jewish men who study the Torah full-time in seminaries have long been granted an annual deferment from military service until the age of 26, at which point they become exempt.

Young ultra-Orthodox women are automatically exempt.

The exemptions date from Israel's founding in 1948, and were meant to allow a group of 400 young people to study sacred texts and preserve Jewish traditions put at risk by the Holocaust.

Today, the ultra-Orthodox number 1.3 million people, according to the Israel Democracy Institute -- bolstered by a fertility rate of more than six children per woman, which far exceeds the national average of 2.5.

Most ultra-Orthodox want the exemptions to be extended to all religious students, saying serving in the military is incompatible with their values.