Hospitals in Yemen have been repeatedly and deliberately attacked, said the International Committee of the Red Cross, and also urged warring factions to respect the sanctity of health facilities.
It said in a statement that Al-Thawra hospital in third city Taez was shelled on November 8, weeks after a hospital run by medical charity Medecins Sans Frontieres was hit in the north.
"Al-Thawra hospital, one of the main health care facilities in Taez, which is providing treatment for about 50 injured people every day, was reportedly shelled several times on November 8," it said.
The Red Cross said there have been "close to a hundred similar" accidents reported since March, when a Saudi-led coalition launched an air war on opponents of President Abedrabbo Mansour Hadi.
"Health facilities are deliberately attacked and surgical and medical supplies are also being blocked from reaching hospitals in areas under siege," said Omar.
In October, air strikes hit the Hayadeen hospital run near the rebel-held city of Saada in northern Yemen, with MSF posting pictures on its Twitter account showing a collapsed roof and rubble.
MSF said there were no deaths, but rights group Amnesty International reported at the time that seven staff members were wounded.
UN chief Ban Ki-moon later denounced the air strikes which he said were carried out by warplanes of the Saudi-led coalition.
The ICRC said attacks on health facilities are "a flagrant violation of international humanitarian law", and deplored the health situation in Taez.
The city in central Yemen has seen heavy fighting in recent weeks between pro-Hadi forces and Iran-backed Shiite Huthi rebels who are also allied with troops loyal to ousted president Ali Abdullah Saleh.
Loyalist forces are inside Taez, while the rebels control the main roads leading into the city.
The ICRC said it was been trying to deliver medical supplies to Taez for nearly two months, "but to no avail".
The rebels seized the capital Sanaa last year and then advanced south to second city Aden, forcing Hadi to flee to Saudi Arabia.
The United Nations says that around 5,000 people have been killed in the Yemen conflict since March.
It is hoping to announce soon a date for talks between the government and the rebels.