Millions of dollars of funding cuts from donors and U.N. cost-cutting could hamper evidence gathering and undermine efforts to seek justice for Rohingya who fled Myanmar, the head of a U.N. investigation said.

Nicholas Koumjian, head of The Independent Investigative Mechanism for Myanmar, said he fears that the scale-back of its work will hurt efforts to bring perpetrators to justice.

"It will affect the ability to convict because we lose capacity," he said in an interview in Geneva. "That would send a message of impunity. It says to perpetrators: don't worry about being charged."