HUNDREDS of Sudanese troops arrived in the southern Yemen port of Aden on Saturday in response to the Houthi rebels’ capture of the central Bayda province.

In a major escalation of the war in Yemen, the Sudanese soldiers were merely the advance guard of a Saudi-led coalition force of 10,000 fighters.

Yemen’s Ansar Allah (the army of God), commonly dubbed the Houthis after the powerful clan that leads it, cleared Bayda of forces loyal to exiled president Abed Rabbo Mansour Hadi on Friday.

The fighting over the province, which lies south of the capital Sanaa and north of Aden, claimed some 550 lives on both sides.

Of the 300 Hadi loyalists killed, 30 were mistakenly targeted by air strikes from the Saudi-led coalition that backs them.

Hadi forces have claimed advances in Marib province, west of Sanaa, while refusing Ansar Allah’s offers of a ceasefire.

Another “friendly fire” incident on Saturday killed at least 20 Hadis and wounded a similar number when air strikes hit an encampment in Southern Taiz province.

The militiamen had just captured the encampment from Ansar Allah. “They thought the Houthis were still there,” one pro-government security official said.

In the northern desert province of Jawf, which borders Saudi Arabia, the Saudis claimed to have killed 13 Houthis in an air raid.

On Friday Unicef, the UN’s children’s fund, reported that more than half a million Yemeni children were at risk from “severe malnutrition” — a three-fold increase since the Saudi-led bombing campaign began in March.