"My dear sister", he goes on to write, "If the political price of your ascension to the highest office in Myanmar is your silence, the price is surely too steep".
The armed forces in Myanmar retain powerful positions - and it is hard for Suu Kyi to exercise control over them.
Long-time friend and confidant, retired Archbishop Desmond Tutu, has also condemned Suu Kyi's mishandling of the crisis.
Desmond Tutu's intervention comes as the United Nations refugee agency announced an estimated 270,000 Rohingya have sought refuge in Bangladesh over the past two weeks.
Discussing the Rohingya situation on Thursday, she said: "I think it's a little unreasonable to expect us to resolve everything in 18 months".
What is even more worrying is that the plight of the Rohingya will follow the same farcical and inhuman path that so many Syrians have suffered recently: that is, both Russian Federation and China might once again use their veto power to protect the government of Myanmar from censure and condemnation at the UN Security Council.
Conservative MP Garnett Genuis called the federal government's response to the persecution "slow and inadequate" despite it being repeatedly raised in the House.
The incident had forced almost 90,000 Rohingya to flee to Bangladesh.
It's Prince George's first day of school!
The condition means she has had to cancel several public engagements, including accompanying George to Thomas's Battersea . And fortunately for Kate, there will be plenty more school runs to do - and, of course, plenty more first days of school.
"Many refugees are stranded in no-man's land between the borders with Myanmar", medical charity Doctors Without Borders (known by its French acronym MSF) said in a statement.
Suu Kyi, who won the Nobel Peace Prize in 1991, receiving the award for "her non-violent struggle for democracy and human rights" while standing up against military rulers.
"We're trying to progress as quickly as possible on the development front, because one of the biggest problems is the matter of very limited resources", she said Thursday.
After the UN Secretary-General António Guterres warned of ethnic cleansing and regional destabilization and sent a rare letter to the Myanmar government, talking of a "humanitarian catastrophe", Suu Kyi finally broke her silence on the issue on September 6 and blamed "terrorists" for "a huge iceberg of misinformation" on the violence in Rakhine state, but did not address the issue of fleeing refugees.
"Myanmar army is carrying out a genocide of the Rohingya with the help of Suu Kyi's government". That intensifies doubts about government claims that members of the persecuted minority have been destroying their own homes.
Turkey said that Burma agreed to allow its aid officials to enter Rakhine state with a tonne of food and goods for Rohingya.
An ethnic Rakhine villager who emerged from the smoke said police and Rakhine Buddhists had set the fires. Rohingya Muslims have long faced discrimination in the majority-Buddhist Southeast Asian country.
The U.S. Embassy in Yangon is discussing the situation with civilian and military authorities, and calling for an end to violence and access for humanitarian groups and journalists, the State Department said.
"We as the humankind have to take action and take the head of the Myanmar state Aung San Suu Kyi and the armed forces' commander-in-chief, Min Aung Hlaing to International Criminal Court (The Hague) over a genocide case so both of them can answer to their hate crimes. You in India are well-versed with this, because India has a large Muslim community and in place like Kashmir, where you face terrorism, the trouble of sorting out the terrorists from the innocent citizen and all those who are not involved in the terrorist movement at all, comes up".
The violence began with insurgent attacks on police August 25 and government forces retaliated with what they called "clearance operations".