Yemen's government says hospitals in the besieged city of Taiz are close to collapse.

The health ministry warned on Saturday of an "imminent health and humanitarian catastrophe," Al Jazeera reported. It said medicines, intravenous fluids, medical supplies and fuel at the city's health facilities are "nearing depletion." Emergency care, surgery, intensive care, kidney dialysis and newborn services could stop, putting patients, injured people, pregnant women and babies "at immediate risk."

The ministry blamed the Houthis, the Iran-backed group that controls much of northern Yemen, for tightening their siege and blocking supplies. Fuel shortages also threaten power for hospitals.

At the same time, the internationally recognized government says its forces are on the attack. On Saturday it said troops were advancing against the Houthis around the Bab al-Mandab strait, France 24 reported. The government launched a counteroffensive a week ago to take back land the Houthis seized last month.

A government military spokesman claimed 1,150 Houthi fighters were killed in nearly 2,000 operations in 24 hours. Al Jazeera said it could not verify that figure.

Saudi Arabia's ambassador to Yemen said Friday the Houthis had lost control of the strait. A Houthi spokesman rejected that, Al-Monitor reported.

Yemen's war has run for more than a decade and has caused one of the world's worst humanitarian crises. The Bab al-Mandab is a narrow sea passage at the southern end of the Red Sea. A large share of world shipping passes through it.

The fighting has widened. The Houthis are blamed for an attack on Riyadh's main airport this week that killed 12 people.

What we know: Yemen's government says Taiz hospitals are near collapse under siege.
What we don't: whether aid will reach the city soon.