Aid agencies warned on Monday of a growing humanitarian crisis including food shortages in Yemen as Saudi-led warplanes hit rebel positions for a third week and rival forces clashed.

In Riyadh, Yemen’s Prime Minister Khaled Bahah was sworn in as vice president at the country’s embassy in front of exiled President Abedrabbo Mansour Hadi.

Hadi, meanwhile, in a New York Times opinion editorial accused Iran of fuelling a “campaign of horror and destruction” by the Shiite Huthi rebels and being “obsessed with regional domination“.

Yemen’s main southern city of Aden saw the heaviest fighting overnight, with medics and military forces saying at least 30 people were killed in clashes.

Farther north, fierce clashes continued in Daleh where 40 rebels and three pro—president fighters have been killed since yesterday, a local official and southern fighters said.

Three children were killed today when a shell hit their house in south Daleh, southern activist Saleh Binlaghbar said.

Residents said warplanes from a Saudi—led coalition pounded the rebel—held presidential complex and other positions in Aden, Hadi’s last refuge before he fled to neighbouring Saudi Arabia as the air war began on March 26.

The Huthis, who have joined with forces loyal to ex—president Ali Abdullah Saleh, advanced on Aden last month after seizing Sanaa last year.

Saudi Arabia has accused Iran, the main Shiite power, of backing the rebel offensive and has rallied support for the coalition from regional allies.

Western powers have also backed Hadi as Yemen’s legitimate ruler, while the United Nations has called for talks to resume.

Human Rights Watch urged the coalition to take “necessary steps to minimise harm to civilians”, urging the bloc and the United States to investigate “alleged laws—of—war violations,” including the bombing of a displaced persons camp last month.