Aung San Suu Kyi remains Myanmar's best hope for change, veteran U.S. mediator Bill Richardson said on Friday, days after he got into an argument with the Nobel laureate and quit an international panel advising her government on the Rohingya crisis.

Richardson said Suu Kyi — whom he described as a long-time friend — had developed a "siege mentality" in her position as Myanmar's State Counsellor, the country's civilian leader, but added that Western governments should continue to engage with her.

"The relationship with the West, with human rights groups, with the United Nations, with the international media is terrible," he said by phone from New Mexico on Friday.