By Agence France-Presse
One-time Suu Kyi ally Richardson was one of five foreign members hand picked by Myanmar's civilian leader to serve on the committee.
But after a three-day visit to Myanmar, Richardson struck out at his hosts, saying he could not in "good conscience" sit on a panel he feared would only "whitewash" the causes of the Rohingya crisis.
He lambasted Nobel Laureate Suu Kyi for an "absence of moral leadership" over Rakhine and described her "furious response" to his calls to free two Reuters journalists arrested while covering the crisis.
A Myanmar government spokesman hit back Thursday, accusing the former New Mexico Governor Richardson of over-stepping the mark in his stinging resignation letter.
"He should review himself over his personal attack against our State Counsellor," government spokesman Zaw Htay told AFP.
"We understand his emotion about the two Reuters correspondents. However, he needs to understand, rather than blaming the Myanmar nation and the State Counsellor."
Zaw Htay said the issue of the arrests was not in Richardson's mandate and he should not have brought it up at his meeting with Suu Kyi.
Myanmar nationals Wa Lone, 31, and Kyaw Soe Oo, 27, face a possible 14 years in prison under the Official Secrets Act for allegedly possessing classified documents that they say were given to them by two policemen.
They are waiting to hear whether they will be granted bail in a protracted case that could take months to even get to trial.
It is thought they had been reporting on atrocities committed by security forces in Rakhine.
Troops backed by hardline Buddhist mobs have torched hundreds of Rohingya villages, forcing nearly 690,000 to flee over the border into overflowing camps in Bangladesh.
They have brought with them consistent testimony of murder, rape and arson in violence the UN and US have condemned as ethnic cleansing.
Richardson's resignation came after Myanmar and Bangladesh failed to meet a January 23 deadline to begin the complex and contested repatriation of refugees.
Richardson joined the Myanmar board as a private citizen, but the US State Department said the Washington administration shares many of his concerns.
After his trip to Myanmar, the diplomat said he was shocked by the disparagement of the media, the UN, human rights groups and the international community by some fellow panel members and Myanmar authorities.