Saudi Arabia, which is leading an air campaign against rebels in Yemen, has pledged to provide exactly the amount of emergency aid to the country as called for in a UN appeal on Friday.
The official Saudi news agency said it has promised $274m (£183m; €255m) in humanitarian aid.
Yemen has been wracked by fighting between Houthi rebels and government troops.
The UN says 150,000 people have been displaced by fighting.
It also says 12 million are short of food.
Saudi King Salman bin Abdulaziz al-Saud announced the aid late on Friday, saying his country would “stand fully by the brotherly people of Yemen”.
A Saudi-led coalition has been launching air strikes against the rebels in 18 of Yemen’s 22 provinces, exacerbating an existing humanitarian crisis.
The UN said 731 people had been killed and 2,754 injured – many of them civilians – in three weeks between March and April. The numbers were likely to be an underestimate, it warned.
A land, sea and air blockade has made it hard not just to assess the damage but to get aid to where it is needed, the BBC’s Arab affairs editor Sebastian Usher says.
Even before the current conflict, 15.9 million people – 61% of the population – were estimated to require some kind of humanitarian aid, according to the UN.
Al-Qaeda in the Arabian Peninsula (AQAP), which is fighting both the rebels and government troops, has also exploited the chaos gripping the country.
AQAP fighters took control of a massive weapons depot in the eastern Hadramawt province on Friday.
Earlier this month, they seized an airport in southern Yemen, and overran the port city of Mukalla.