The UN on Tuesday called for a "humanitarian" truce in air strikes and fighting in Yemen as it seeks to deliver aid to civilians trapped in the capital Sanaa.
"I ... sent a message asking for a truce, a peace pause, a humanitarian pause, for the parties to stop shooting, stop fighting, stop air strikes, so the people can go to hospitals, can go to seek safety ... and go to also find a place for water and food," UN humanitarian coordinator Jamie McGoldrick told reporters in Geneva by phone from Sanaa.
"Our ability to get to people over the last five days has been impeded because of the air strikes, because of the fighting, and our life-saving support activities were blocked," he said.
McGoldrick's statement came a day after Yemen's Huthi rebels killed former president Ali Abdullah Saleh as he fled the capital following the collapse of their uneasy alliance.
For the five previous nights, heavy fighting had rocked Sanaa, leaving at least 234 people dead and 400 wounded, according to the International Committee of the Red Cross.
After the assassination, Saudi-led warplanes pounded the capital before dawn Tuesday as the rebels moved to consolidate their control over the city.
"What happened... because of our inability to move in the city during the five days -- the UN agencies, Red Cross and NGOs -- we were unable to do our life-saving treatments," McGoldrick said.
"Now the uncertainty continues and despite what happened yesterday, we don't know if we can start doing our operations or whether we have to wait for some time," he added.
Yemen's war has left thousands dead since 2015, sparking what the United Nations now labels the world's worst humanitarian crisis, and has deepened tensions between Middle East rivals Saudi Arabia and Iran.
McGoldrick said a UN team would travel to Riyadh "quite soon".
Saudi Arabia imposed a blockade on Yemen's ports after a Huthi missile was intercepted near Riyadh airport on November 4.
The blockade has been eased only partially despite repeated calls from the UN.