The UN on Tuesday called on the Saudi-led coalition to open all of Yemen's seaports in order to let humanitarian aid through.
"We would ask that the coalition opens all the seaports as a matter of emergency and allows humanitarian and other supplies to move as well as aid workers," UN Yemen Resident and Humanitarian Coordinator Jamie McGoldrick told reporters in Geneva by phone from Amman.
On Monday, Riyadh said the Saudi-led coalition would reopen Yemen's ports, days after closing them over a ballistic missile attack reportedly perpetrated by Houthi rebels on the capital.
However, the port of Hodeidah on the western coast, where nearly 80 percent of Yemen's food imports have gone through, is still closed.
Noting that there were three weeks of vaccines left in the country, McGoldrick said "humanitarian supplies are dangerously low".
The north of the country has 20 days' stocks of diesel and 10 days' stocks of gasoline, McGoldrick said.
Earlier this month, the Saudi-led coalition closed access to Yemeni ports following a ballistic missile attack toward Riyadh by Houthi rebels. The coalition argues that the closure was needed to stop arms reaching to the Houthi rebels.
On Monday, thousands of Yemenis took to the streets of the capital Sanaa to protest the closure of the country's ports by the Saudi-led coalition.
The demonstrations came a day after Houthi rebels threatened to attack warships and oil tankers from the Saudi-led coalition in retaliation to the blockade.
Last week, the World Health Organization (WHO) warned that more Yemeni civilians would die because of the closure of the Yemeni ports.
Impoverished Yemen has remained in a state of civil war since 2014, when Houthi rebels overran much of the country, including Sanaa.
The conflict escalated when Saudi Arabia and its Arab allies launched a massive air campaign in 2015 aimed at reversing Houthi military gains and strengthening Yemen's embattled government.
