US Secretary of State Rex Tillerson urged Mynmar's army chief Thursday to help end the violence in Rakhine state that has forced hundreds of thousands of Rohingya Muslims to flee.

In a phone call with Min Aung Hlaing, Tillerson expressed "concern about the continuing humanitarian crisis and reported atrocities in Rakhine", according to a statement by State Department spokeswoman Heather Nauert. 

"The Secretary urged Burma's security forces to support the government in ending the violence in Rakhine state and allowing the safe return home of those displaced during this crisis, especially the large numbers of ethnic Rohingya," she added.