Israel's Supreme Court has ruled against an extension to a law that allows strictly Orthodox Jews to defer or limit their army service.

The Tal Law, which came into effect ten years ago, was ruled unconstitutional. It had enabled Israel's full-time yeshivah students to continue their studies, and delay their national service until they were 23, at which point they could continue their studies or perform only a year of service. Israelis are conscripted into the army at the age of 18, with women usually obliged to serve two years and men three.

The law will expire in August, but the Supreme Court ruled that the system should be scrapped rather than renewed in its current form.

According to Ha'aretz there are about 62,000 yeshivah students who would now be eligible to begin their service this summer.

The outgoing High Court President Dorit Beinisch, whose successor criticised the ruling, said: "Originally the legislation harboured the hope that the law would launch a social process that without coercion would encourage ultra-Orthodox people to serve in the military or take part in national civil service. These hopes were dashed."

The Tal Law is one of many issues that highlight the divide between Israel's secular and religious. Many secular Israelis resent the fact that they cannot secure exemptions from army service in the way that religious men and women can.

The ruling could destabilise the coalition between Benjamin Netanyahu's Likud party and its Shas partners. But Shas spokesman Yakov Betzalel dismissed concerns and said he believed a new deal could be made.

Ehud Barak, now defence minister but prime minister at the time the law came into effect, acknowledged that the law "did not meet expectations, nor did it lead to the required changes ... concerning equally sharing the burden."