ADEN (Reuters) - Shells fired by Yemen's dominant Houthi group killed 18 people near the southern port city of Aden early on Wednesday, local officials and witnesses said, while the United Nations warned that a dengue fever outbreak in Aden was rapidly spreading.
Yemen, which has long struggled with poverty and hunger, has descended into a fullblown humanitarian crisis since a war erupted between the Houthis and allies of exiled President Abd-Rabbu Mansour Hadi, drawing in neighboring Saudi Arabia.
The United Nations on Wednesday raised Yemen to its highest level humanitarian crisis, placing it alongside emergencies in South Sudan, Syria and Iraq.
"More than 21.1 million people, over 80 percent of Yemen's population, now need some form of humanitarian assistance," U.N. spokesman Farhan Haq said.
The United Nations also said in a report on Tuesday that an average of 150 new cases of dengue fever and around 11 deaths were being reported daily.
The northern Houthi fighters, who have seized large parts of Yemen in recent months, advanced towards Aden in March, prompting Hadi, who had taken refuge there, to flee to Saudi Arabia.
Since then Aden has been host to almost daily clashes between the Houthis and local resistance fighters allied with Hadi. Thousands have been killed or wounded.
Residents of Aden's Mansoura district said mortar shells apparently fired indiscriminately by Houthis stationed in a field to the north, killed seven people sheltering at a hotel and 11 more at a market.
They said one resident in his 30s, Atef al-Somali, was killed while trying to buy food for suhoor -- a meal Muslims eat early in the morning before they resume their dawn-to-dusk fast during the holy month of Ramadan.
At least 30 other people were wounded in the attack, local officials said.
Houthi officials were not immediately available to comment on the report.
Aden, a city of more than 1 million people, is facing shortages of food, fuel and medical supplies.
The United Nations quoted Aden health officials as saying that 8,000 people had contracted dengue fever in Aden since the crisis began in March.
The U.N. report also said that 590 have died from the disease, five times what was reported two weeks ago. Dengue fever outbreaks had also been reported in eastern Hadramout and western Hudaydah.
Yemen's political turmoil deepened on March 26 when a Saudi-led coalition began a campaign of air strikes against the Houthis and their allies.
Reporting by Mohammed Mukhashaf, additional reporting by Michelle Nichols at the United Nations; Writing by Sami Aboudi; Editing by Raissa Kasolowsky, Toni Reinhold