Reports of Saudi Arabia and the United Arab Emirates failure to make good on funding pledged made in February have led to Yemenis dying from cholera and other illnesses.
The UN's emergency relief coordinator, Mark Lowcock, told the UN Security Council most of the 40 countries that made pledges had stumped up aid cash, but Abu Dhabi and Riyadh were holding out.
Both countries have pledged 500million towards the 2.6 billion government promised contribution.
Mr Lowcock said the response plan is currently just 34 percent funded.