Aung San Suu Kyi remains Myanmar's best hope for change, veteran US mediator Bill Richardson said on Friday, days after he got into a fight 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 told Reuters by phone from New Mexico on Friday.

"And I think Aung San Suu Kyi has brought this upon herself, the constant disparagement of the international community, which I think can be helpful to her ... She seems isolated. She doesn't travel much into the country. I think she's developed a classic bubble."

Richardson said he resigned from the advisory board on Wednesday, during its first visit to troubled Rakhine State, saying it was conducting a "whitewash". Suu Kyi's office said on Thursday her government had asked Richardson to step down and accused him of pursuing "his own agenda".