General Joseph Aoun's intervention, rare for a Lebanese army chief, comes after the government approved a budget aimed at unlocking billions of dollars in aid that an official source said includes a three-year army recruitment freeze.

"The ban on recruiting soldiers or cadets, and the ban on dismissal, will have negative consequences on the military institution," Aoun said in a statement published by the army.

Lebanon is one of the world's most indebted countries and the government plan is expected to trim the country's deficit this year to 7.59 percent.

Donors at the so-called CEDRE conference last year pledged $11 billion in aid and soft loans to Lebanon, which vowed to reduce its public spending.

Aoun said the army has already been adopting a stringent approach to spending and last year returned part of its budget to the state coffers.

"The army is the backbone of Lebanon, we do not exaggerate in saying that it guarantees (the country's) security and stability. Its mission is not limited to times of war and conflicts," he said.

"Despite the current security stability, significant challenges remain, such as those at our eastern, southern or maritime borders," Aoun added.

Lebanon has been hit by repeated political deadlocks in recent years and the economic woes have been compounded by the devastating war in neighbouring Syria.

It is also technically still at war with Israel, with United Nations peacekeepers stationed on the frontier.

There have been numerous protests in recent weeks against the austerity measures by Lebanese government workers, including by retired soldiers concerned about possible pension reductions.

Civil servant salaries are to be cut under the new budget, which would also introduce a 2-percent tax on imports and increase taxes on interest income from bank deposits from seven to 10 percent.

The plan still needs to be ratified by parliament, giving lawmakers an opportunity to table amendments.