To this day, however, the Myanmar government has refused to allow United Nations investigators and the international media to freely visit northern Rakhine. Aid groups have been similarly stymied. Last month, Yanghee Lee, the United Nations special rapporteur on Myanmar who has been a vocal critic of the military crackdown, was denied a visa to the country.

Mr. Richardson, a former United Nations ambassador under President Bill Clinton, has a reputation as a diplomatic troubleshooter. He said last week en route to Myanmar that during his visit he intended to secure the release of the Reuters journalists, who were seized in December.

“One of my objectives in joining the advisory board was to be helpful and try to sort out real, long-term policy solutions,” Mr. Richardson said. “But I discovered that this board was being used as a cheerleading squad for the government.”

Mr. Richardson said he had been “very shocked” by how Ms. Aung San Suu Kyi and other board members had disparaged human rights groups, the United Nations and international media organizations over how the Rohingya disaster had been presented to the world.

He was particularly critical of the advisory board’s chairman, Surakiart Sathirathai, a Thai politician who, Mr. Richardson said in a statement, had sought to “avoid the real issues at the risk of confronting our Myanmar hosts.”

The board’s agenda, Mr. Richardson said in the statement, was “devoid of any meaningful engagement with the local communities in Rakhine, whose people the advisory board is meant to serve.”

Mr. Surakiart could not immediately be reached for comment.

A spokesman for Myanmar’s government, U Zaw Htay, said that Mr. Richardson did not understand the “rules and regulations” of the board’s meeting with Ms. Aung San Suu Kyi and accused him of overstepping his mandate.