Israel began mobilizing tens of thousands of reservists on Tuesday as part of its plan to widen its offensive in Gaza City, which has sparked opposition domestically and condemnation abroad.

Israeli Army Radio said that some 40,000 reservists would report for duty Tuesday for the Gaza City offensive. 

The beginning of September call-up, announced last month, comes as ground and air forces press forward and pursue more targets in northern and central Gaza, striking parts of Zeitoun and Shijaiyah — two western Gaza City neighborhoods that Israeli forces have repeatedly invaded during the 23-month war against Hamas militants.

Zeitoun, once Gaza City's largest neighborhood with markets, schools and clinics, has been transformed over the past month, with streets being emptied and buildings reduced to rubble as it becomes what Israel's military last week called a "dangerous combat zone."

Gaza City is Hamas' political and military stronghold and, according to Israel, still home to a vast tunnel network despite multiple incursions throughout the war. It is also one of the last refuges in the northern strip, where hundreds of thousands of civilians are sheltering, facing twin threats of combat and famine.

The reservist call-up will be gradual and include 60,000, Israel's military said last month. It will also extend the service of an additional 20,000 already on active duty.

Since the world's leading authority on food crises declared last month that Gaza City was experiencing famine, malnutrition-related deaths have mounted. Gaza's Health Ministry said on Tuesday that a total of 185 people died of malnutrition in August — marking the highest count in months.

A total of 63,557 Palestinians have been killed in the war, according to the ministry, which says another 160,660 people have been wounded. The ministry doesn't differentiate between civilians and combatants in its count, but says women and children make up around half the dead.

The ministry is part of the Hamas-run government but staffed by medical professionals. U.N. agencies and many independent experts consider its figures to be the most reliable estimate of war casualties. Israel disputes them, but hasn't provided its own toll.

The war started with an attack on Oct. 7, 2023, on southern Israel in which Hamas-led militants killed 1,200 people, mostly civilians, and took 251 people hostage. Forty-eight hostages are still inside Gaza, around 20 of them believed by Israel to be alive, after most of the rest were released in ceasefires or other deals.

This report contains material from The Associated Press and Reuters.