The Saudi-led coalition fighting rebels in Yemen shut down the country's land, sea and air borders a week ago in response to a missile attack by the Iran-backed Houthis that was intercepted near Riyadh. "Seven million people are already on the brink of starvation and the blockade will only bring them closer to it".
Millions of lives were at risk because of the blockade, United Nations humanitarian coordinator for Yemen, Jamie McGoldrick, said to reporters in Geneva by telephone from Amman.
"The humanitarian impact of what is happening here right now is unimaginable", he told reporters in Geneva in a phone conference.
McGoldrick said the Saudi plan to supply Yemen through the Saudi port of Jizan in the north and Aden in the south was too complicated, dangerous, slow and expensive, adding an estimated $30 per tonne to every shipment.
The U.S.is supporting a Saudi Arabia-led coalition in the conflict, with intelligence, aerial refueling and the sale of weapons.
The announcement from the Saudi mission at the United Nations came after the coalition fighting Yemen's rebels, known as Houthis, faced widespread global criticism over the closure, with the U.N. and over 20 aid groups saying it could bring millions of already suffering people closer to "starvation and death".
"We would ask that the coalition opens all the seaports as a matter of urgency and allows humanitarian and other supplies to move, as well as the movement of aid workers", he said.
The blockade "is complicating what is already a catastrophic situation", McGoldrick said.
It says: "The first step in this process will be taken within 24 hours and involves reopening all the ports in areas controlled by" Yemen's internationally recognized government, which the coalition backs.