The draft issue is especially sensitive as Israel's armed forces, made up mostly of teenaged conscripts and civilians mobilised for reserve duty, wage a nearly six-month-old war in Gaza to try to eliminate the Islamist group Hamas that rules the Palestinian enclave.

One senior Israeli official estimated that 5% of the population was taking part in the conflict, which has spread to the Lebanese front and drawn missile salvoes from Yemen.

Yet the ultra-Orthodox, Israel's fastest-growing religious minority, have a waiver from conscription. The Supreme Court scrapped this in 2018 in the name of equality. Parliament failed to come up with a new arrangement, and a government-issued stay on mandatory conscription of ultra-Orthodox expires on March 31.

Those favouring a review of the exemption include Netanyahu's defence minister and other cabinet members managing the war. They predict months of more fighting that will strain manpower and stoke public demands for more equitable call-ups.

But ultra-Orthodox parties in the governing coalition, to which the conservative leader has long looked for support, want to preserve the waivers, which are designed to keep their constituents in seminaries and preserve the religious lifestyle.

In a letter to the Supreme Court published by his office, Netanyahu said he had "made salient progress on the draft issue" but asked for a 30-day extension "in order to draft agreements".

The war against Hamas militants has dominated the government's attention and is now at a decisive point, he said.

There was no immediate comment from court spokespersons.

The ultra-Orthodox make up 13% of Israel's 10 million population, a figure expected to reach 19% by 2035 due to their high birth rates. Economists argue that the waiver from the draft keeps some unnecessarily in seminaries and out of the workforce, spelling a growing welfare burden for middle-class taxpayers.

Israel's 21% Arab minority are also mostly exempted from the draft, under which men and women are generally called up at age 18, with men serving three years and women, two.

(Writing by Dan Williams; Editing by Frances Kerry)