Hundreds of thousands of Rohingya Muslims who have fled violence and persecution in Myanmar will be allowed to return, Aung San Suu Kyi has said.
The country's de facto leader gave her "strong commitment" during a meeting with Foreign Office Minister Mark Field.
The UN has described the treatment of the Rohingya in Myanmar as "ethnic cleansing" with an estimated 400,000 fleeing across the border into Bangladesh in the wake of violence from nationalist militias, who have torched dozens of villages in Rakhine State, killing and gang raping Muslims in the their path.
Critics say Myanmar's government itself has stoked ethnic tensions which have seen ultra-nationalist Buddhist mobs surround many Muslim Rohingya villages.
The violence has driven the Rohingya to flee Buddhist-majority Myanmar, with many of them packed into existing camps or huddled in makeshift settlements that have mushroomed along roadsides and in open fields across Cox's Bazar district on the border with Bangladesh.
Despite the 72-year-old's pledge, Mr Field questioned "how many [Rohingya] will feel confident enough with the security implications of what has happened in the country to return?"
He added that the treatment of the Rohingya in Myanmar in recent weeks "is an absolute and unacceptable tragedy".
Ms Su Kyi - a Nobel peace prize winner - has faced growing international condemnation for her refusal to condemn the actions of Myanmar's security forces, instead arguing that there has been "an iceberg of misinformation" surrounding the reports from refugees of their villages being burned and of people being slaughtered.
However, following his meeting with Ms Suu Kyi in Myanmar's capital, Naypyidaw, Mr Field did concede that she was in a difficult position, since much power still remains in the hands of Myanmar's military.
The military ruled the south-east Asian country alone until two years ago.
As a state counsellor - a position akin to a prime minister - Ms Suu Kyi does not have authority over the military.
Mr Field went on to say that Ms Suu Kyi remained the best hope for democracy in Myanmar.
He continued: "She is in a difficult position. Under the constitution the military remains very powerful. There are only small steps that have taken place in recent years towards democracy.
"She finds herself treading a fine line between the international criticism, which we have obviously seen in the last six months, but also public opinion in Burma which remains very strong anti-Rohingya.
"Whatever else happens, she is the best hope for ongoing democracy in Burma. What would be calamitous would be for it to fall back into military dictatorship."
Mr Field added: "She is becoming increasingly aware, because I am not the only person who is telling her this, that there is much that needs to be done if the international community is going to have confidence is going to be moving into the right place and the right direction."
In a televised speech earlier in September, Ms Suu Kyi said she does not fear "international scrutiny" of her government's handling of the growing Rohingya crisis.
In the 30-minute address, Ms Suu Kyi insisted that most Muslims had not fled the state and that violence had ceased.
She added that it was “sad” that the world was concentrated on just one of the country's problems.
The leader of the National League for Democracy party continued that she was "concerned" about the allegations of violence and wanted "to find out what the real problems are. There have been allegations and counter-allegations.
"We have to listen to all of them. We have to make sure those allegations are based on solid evidence before we take action."
During her speech, she also said she wanted to find out why "this exodus" of Muslims fleeing across the border to Bangladesh is happening.
Last week, Foreign Secretary Boris Johnson called on Ms Suu Kyi to "show the leadership she is capable of to try and heal that terrible situation".