The UN humanitarian coordinator for Yemen called Saturday for regular humanitarian access to parts of the battleground city of Taez that are besieged by Iran-backed rebels.
Jamie McGoldrick said he saw some food, cooking gas and other commodities being brought into the city where pro-government forces are holed up.
"I appeal to authorities and groups to work with the United Nations to establish a mechanism that will allow regular and sustained access of these goods and more into the city," he said in a statement.
He said access to three districts of the southwestern city had been difficult for months and the UN is seeking "mechanisms with parties on the ground to ensure sustained, unfettered and unconditional access."
Shiite Huthi rebels and allied fighters loyal to former president Ali Abdullah Saleh have laid siege to Yemen's third city for months.
The insurgents overran the capital Sanaa unopposed in September 2014 and expanded their control across several regions.
Loyalists backed by a Saudi-led coalition have recaptured Aden and four other southern provinces since July, as well as most of Marib province, east of the capital.
McGoldrick said basic services are scarce in Taez, while hospitals are short of medical supplies.
"Everywhere I went I saw the trauma the conflict is causing to the women, men and children," he said.
UN children's fund (UNICEF) representative Julien Harneis, who also went to Taez, told reporters that the conditions of displaced people in areas near the city were "absolutely terrible".
More than 5,800 people have been killed in Yemen since the Saudi-led bombing campaign against rebels began in March, about half of them civilians, according to the United Nations.