Johannesburg: Retired South African cleric and anti-apartheid campaigner Archbishop Desmond Tutu urged Myanmar leader and fellow Nobel Laureate Aung San Suu Kyi on Thursday to intervene to help Rohingya Muslims fleeing her country.

Western critics have accused Suu Kyi of not speaking out for the Rohingya, who have been fleeing to neighbouring Bangladesh, following an army counter-offensive against militant attacks.

Tutu said in an open letter to Suu Kyi that: "I am now elderly, decrepit and formally retired, but breaking my vow to remain silent on public affairs out of profound sadness about the plight of the Muslim minority in your country, the Rohingya."

"My dear sister: If the political price of your ascension to the highest office in Myanmar is your silence, the price is surely too steep ... We pray for you to speak out for justice, human rights and the unity of your people. We pray for you to intervene," Tutu wrote.

Tutu, 85, has been living with prostate cancer for nearly two decades and has largely withdrawn from public life.

The Rohingya comprise some 1.1 million people who have long complained of persecution and are seen by many in Buddhist-majority Myanmar as illegal migrants from Bangladesh.

"We have to take care of our citizens, we have to take care of everybody who is in our country, whether or not they are our citizens," Suu Kyi said earlier on Thursday in comments to Reuters Television's Indian partner, Asian News International.

Suu Kyi, who won the Nobel Peace Prize in 1991 as a champion of democracy, did not refer specifically to the exodus of the minority Rohingya.