The United States is worried about the "tragedies" in Myanmar affecting Rohingya Muslims and US authorities are pressing government leader Aung San Suu Kyi and Myanmar's military leaders to stop the crackdown, US Ambassador to the United Nations Nikki Haley said on Thursday.

"Not only have we pressed her, we pressed the military," Haley told reporters, referring to Suu Kyi. She said US Joint Chiefs of Staff Chairman General Joseph Dunford was calling the head of Myanmar's military to say "this cannot continue."