The U.N. humanitarian chief on Thursday called the situation in Myanmar after Cyclone Nargis «increasingly desperate» and estimated that 1.5 million people have been severely affected, according to AP. «There is a real danger that an even worse tragedy may unfold if we cannot get the aid that's desperately needed in quickly,» Undersecretary-General John Holmes warned. While four relief flights from the U.N. World Food Porgram arrived in the capital, Yangon, on Thursday, he said progress has been limited trying to obtain visas and provide emergency supplies. «The frustrations have been growing that this humanitarian response is being held back because of difficulties of access in different ways,» Holmes said. Secretary-General Ban Ki-moon said he was «deeply concerned about the welfare of the people of Myanmar at this time of national tragedy» and called on Myanmar's government to postpone its planned referendum on a new constitution two days from now and «focus instead on mobilizing all available resources and capacity for the emergency response efforts.» Holmes said U.N. officials were pressing for speedy access but he warned that any «confrontation» with Myanmar's military rulers would not help those desperately in need of help. «The humanitarian situation as you know is increasingly desperate on the ground, in the delta, because of the conditions that are obtained there,» Holmes said. «The number of people that have been affected _ we estimate that number at about 1.5 million people severely affected by the disaster.»