As of May 15, 1,849 people had been killed and 7,394 had been injured, the UN humanitarian agency said citing numbers from Yemen health facilities.
The UN has repeatedly stressed that many of those injured and killed do not pass through health facilities, meaning the actual toll could be higher.
The announcement came as witnesses reported that Saudi-led warplanes hit Yemeni rebels and their allies in Sanaa, in the first strikes on the rebel-held capital since the end of a five-day humanitarian truce on Sunday.
The Saudi-led coalition has waged an air war on the rebels since late March in an effort to restore the authority of exiled President Abedrabbo Mansour Hadi, who is now based in Riyadh.
"The humanitarian pause in Yemen was not long enough to reach all those in need of food," Elisabeth Byrs, spokeswoman for the UN World Food Programme, told reporters.
She said WFP had managed to deliver food to only 400,000 people during the pause, just over half of the 738,000 it had aimed to help.
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"WFP is appealing for a series of predictable breaks in the conflict to deliver desperately needed aid," she said.
UN refugee agency spokesman Adrian Edwards meanwhile said the humanitarian pause had allowed all six of the planned UNHCR aid-loaded flights to land safely in Sanaa.
The pause, he told reporters had also allowed the agency to carry out around 40 assessments on the ground across Yemen, which had "exposed enormous difficulties for thousands of civilians displaced by conflict."
The assessments revealed that the violence had forced far more people to flee their homes since previously thought, he said.
The number of people displaced since late March within the conflict-ravaged country is now estimated to be more than 545,000, he said, compared to the 450,000 announced last Friday.
They join some 330,000 people already internally dispaced before the latest conflict, and some 250,000 Somali refugees inside Yemen believed to be impacted by the fighting, Edwards said.
Around 29,000 other Yemenis have fled to neighbouring countries, he said.