Myanmar's de facto leader Aung San Suu Kyi has "a last chance" to stop ethnic cleansing, UN chief Antonio Guterres told the BBC in an exclusive interview.

He said: unless Suu Kyi acts now and intervenes, "the tragedy will be absolutely horrible".

"If she does not reverse the situation now, then I think the tragedy will be absolutely horrible, and unfortunately then I don't see how this can be reversed in the future," he said.

The UN has warned the offensive could amount to ethnic cleansing. Myanmar says it is responding to last month's deadly attacks by militants and denies it is targeting civilians.

UN Secretary General Antonio Guterres has also said that the Rohingyas should be allowed to return.

Aung San Suu Kyi - a Nobel Peace Prize laureate who spent many years under house arrest in the junta-run Myanmar (Burma) - is now facing growing criticism over the Rohingya issue.

Guterres' warning comes after Bangladesh said it was now limiting the movement of more than 400,000 Rohingya who have fled from Myanmar.