Government forces say dozens of Houthi fighters killed in southwestern governorate during battles for strategic highlands.

Yemen’s government-aligned forces say they have repelled Houthi attacks along several fronts in the southwestern governorate of Taiz as heavy fighting continues in the Arab world’s poorest country.

Colonel Majid al-Nuzaili, spokesman for the Saudi Arabia-backed government forces, said on Thursday that the Iran-aligned Houthis launched coordinated attacks on Wednesday night in a bid to reach positions on a key road connecting the Aden, Lahj and Taiz governorates.

But government forces repelled the attacks, killing and wounding dozens of Houthi fighters, he said.

There was no immediate comment from the Houthis on the government’s report.

The renewed hostilities come amid mounting regional tensions set off by the war launched by the United States and Israel against Iran.

The Houthis, who seized Yemen’s capital, Sanaa, in 2014, are fighting government-aligned forces for control of the strategic highlands in the country’s southwest, including the Kahboub Mountains in the Taiz and Lahj governorates. They took control of the port city of Mocha and the Red Sea coast this month.

Control of the Kahboub Mountains, which overlook the strategic Bab al-Mandeb strait and Mayyun Island in the Red Sea, would allow the Houthis to sever the coast from the remaining government-held south.

On Tuesday, government-aligned forces said they had thwarted Houthi attacks in the mountains and taken full control of Mount Qarfan, which overlooks valleys linking southern Taiz with the western coast.

The Houthis said on Wednesday that Saudi forces had carried out 52 air strikes and missile attacks on the Hodeidah, Taiz, al-Bayda, Marib and Saada governorates, causing deaths and injuries, including among women and children.

They said Saudi forces had carried out 988 attacks since the latest escalation began, but they did not say how many people had been killed. Saudi Arabia did not comment on the claim.

The Houthis have fired dozens of missiles and drones at Saudi Arabia in recent weeks, including a strike on the capital, Riyadh, on Saturday.

On Wednesday, Saudi Civil Defence authorities issued alerts warning of potential attacks in Jazan and Najran, two provinces that border Yemen. No further details were given.

Ahmed el Shalfi, Al Jazeera’s Yemen affairs editor, said he expected the fighting to be prolonged.

“The Houthis are determined to hold on to their important gains in the western coast in Mocha and Bab al-Mandab while the government forces are equally determined to drive them out of these places or to defend the highland positions for fire control over the coast and these areas,” he said. “So the war between the two sides is a back and forth. That could well continue and drag on and could also involve attrition on all sides.”

Aid groups said the humanitarian toll is mounting in Yemen.

The World Health Organization said this week that 674 people had been killed and almost 3,000 injured since August 6, including 164 deaths and 516 injuries from September 13 to 18 alone. More than 158,000 people have also been displaced, according to Yemen’s Executive Unit for the Management of Displaced Persons Camps.