Five women who won the Nobel peace prize have told Aung San Suu Kyi she has a personal and moral responsibility to defend the Rohingya people in Burma.

In a letter the laureates accuse the de-facto Burmese leader of indifference over the plight of the Muslim minority – thousands of whom have been killed while hundreds of thousands of others fled to neighbouring Bangladesh.

“As a fellow Nobel Laureate, a worldwide icon for the universal freedom and human rights, and now State Counsellor and de-facto Prime Minister of Burma, you have a personal and moral responsibility to uphold and defend the rights of your citizens,” the Nobel Women’s Initiative wrote.

“How many Rohingya have to die; how many Rohingya women will be raped; how many communities will be razed before you raise your voice in defence of those who have no voice? Your silence is not in line with the vision of ‘democracy’ for your country that you outlined to us, and for which we all supported you over the years.”

Five Nobel laureates signed the letter earlier this week – Mairead Maguire, from Northern Ireland; Jody Williams from the US; Shirin Ebadi from Iran; Leymah Gbowee from Liberia; and Tawakkol Karman from Yemen.

According to the United Nations 270,000 Rohingya Muslims have crossed into neighbouring Bangladesh in the past two weeks.

The exodus began after Rohingya insurgents attacked police posts in Burma, leading the military to respond with “clearance operations” to root out fighters hiding in villages in Rakhine state, prompting accusations of ethnic cleansing.

Ms Maguire said the Nobel Women’s Initiative had been in contact with Ms Suu Kyi since her release in 2010 and raised concerns about the Rohingya people with her in person at the UN last year.

Rohingya refugees – in pictures Show all 15 1 /15 Rohingya refugees – in pictures Rohingya refugees – in pictures A young girl and a baby wade through mud after arriving in Whaikhyang, Bangladesh from Burma on 10 September Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya refugees walk through a camp in Whaikhyang, Bangladesh after arriving from Burma Dan Kitwood/Getty Images Rohingya refugees – in pictures A young Rohingya refugee gathers firewood after arriving in Whaikhyang, Bangladesh from Burma Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya refugees wait for sacks of rice to be distributed in Whaikhyang, Bangladesh Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya Muslim refugees arrive on a boat in Whaikhyang, Bangladesh after crossing from Burma on 8 September Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya Muslim refugees react after being re-united with each other after arriving in Whaikhyang, Bangladesh on a boat from Burma Getty Rohingya refugees – in pictures Rohingya Muslim refugees walk along the remains of a road after arriving in Whaikhyang, Bangladesh on a boat from Burma Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya Muslim refugees wade through water after arriving in Whaikhyang, Bangladesh by boat from Burma Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya Muslim refugees wade through water after arriving in Whaikhyang, Bangladesh by boat from Myanmar Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya Muslim refugees stand in the rain after arriving in Whaikhyang, Bangladesh by boat from Burma Dan Kitwood/Getty Images Rohingya refugees – in pictures Indian children hold placards and shout slogans during a protest against the alleged persecution of the Rohingya Muslims in Burma EPA/Raminder Pal Singh Rohingya refugees – in pictures Supporters of the Difa-e-Pakistan Council (DPC), an Islamic organisation, listen to their leaders' speeches against Burma's persecution of Rohingya Muslims, during a demonstration in Karachi Reuters/Akhtar Soomro Rohingya refugees – in pictures Hundreds of Iranians take part in a protest against violence in Myanmar after weekly Friday prayers, in Tehran EPA/Abedin Taherkenareh Rohingya refugees – in pictures Indonesian Muslim activists hold placards and shout slogans during a protest against the alleged persecution of the Rohingya minority in Magelang, Central Java, Indonesia EPA/Ali Lutfi Rohingya refugees – in pictures Members of an Islamic organisation shout slogans against the Burma government during a protest in Dhaka, Bangladesh EPA

“We have been trying really to do something and speak on their behalf,” Ms Maguire said. “We will continue to do that. We just hope out of her conscience she will realise that she has to speak and that this is ethnic cleansing that is going on.”

In the letter the laureates praised Ms Suu Kyi for her “struggle for democracy, defiant activism and unimaginable and inspiring sacrifices”.

But they called on her to take a firm stand on the crisis and recognise the Rohingya people as Burmese citizens with full rights.