IDF Chief of Staff Gabi Ashkenazi expressed support on Tuesday for a national service system that would draft all Israelis, some of whom the Israel Defense Forces would select to serve in the army.

Such a move is needed because the number of recruits has decreased over the last several years, in keeping with lower overall birth rates and immigration rates and a rise in the Arab and ultra-Orthodox populations, members of which do not generally serve in the army, he told high school principals at conference in Jerusalem on preparing for military service.

In another decade or two, "There will be a reality in which perhaps only a few will enlist in the IDF, and there's not just a security need here, but also a social need, social justice," Ashkenazi said.

The changing demographic situation requires "new models of service" that the IDF must construct, along with government leaders, he said.

The model Ashkenazi described would require all Israelis, including Arabs and the ultra-Orthodox, to sign up for a national service that could include military service for suitable candidates.

"The IDF gets first pick, and chooses the people it needs based on clear criteria," the IDF chief said. The other draftees would then become candidates for civil service selection, and could serve in the police force or a firefighting unit, he said. Referring to an area in the north that is largely populated by Arabs, Ashkenazi added: "There shouldn't be anyone who can argue that he can't serve at a fire station in Wadi Ara even though he lives there."

The IDF has not laid the groundwork for the recruitment change espoused by Ashkenazi, military officials said.

They said the chief of staff was primarily trying to generate public debate and encourage renewed thinking about the national service.

The IDF has already taken several steps to increase the declining number of new recruits, including reversing its longstanding rejection of candidates with criminal records, low education levels and physical challenges.

The army is also trying to recruit more ultra-Orthodox soldiers, about 1,000 of whom have taken on technology-related jobs in the army this year.