United Nations secretary-general says as many as 200,000 Rohingya need to be relocated due to monsoon rain threat.

UN Secretary-General Antonio Guterres has said he heard “unimaginable” accounts of atrocities during a visit on Monday to vast camps in Bangladesh that are home to a million Rohingya refugees who fled violence in Myanmar.

Guterres described the situation for the persecuted ethnic minority as “a humanitarian and human rights nightmare”, as he prepared to tour makeshift shelters crammed with people who escaped a Myanmar army operation last year that the UN has called a “textbook case of ethnic cleansing”.

“In Cox’s Bazar, Bangladesh, I’ve just heard unimaginable accounts of killing and rape from Rohingya refugees who recently fled Myanmar. They want justice and a safe return home,” Guterres wrote on Twitter.

He said that as many as 200,000 Rohingya in the camps need to be relocated, as the monsoon season threatens their safety.

The safety of the Rohingya refugees during this monsoon season is priority one. As many as 200,000 need to be relocated. We cannot allow the monsoons to wash away the hopes of the Rohingya refugees I met today in Bangladesh. pic.twitter.com/uukLfdfADm — António Guterres (@antonioguterres) July 2, 2018

“The Rohingya are one of the most discriminated against and vulnerable communities on Earth,” he said in a tweet before his visit to the camps in southern Bangladesh.

Al Jazeera’s Mohammed Jamjoom, reporting from Cox’s Bazar, said that the visit highlights the “dire” situation of the Rohingya refugees in Bangladesh.

“This is a population that is already very vulnerable,” he said, noting that a “torrential downpour” was battering the area on Monday.

Accompanied by the head of the World Bank, Jim Yong-kim, Guterres called it a “mission of solidarity with Rohingya refugees and the communities supporting them. The compassion & generosity of the Bangladeshi people shows the best of humanity and saved many thousands of lives”.

Nearly 700,000 Rohingya fled Myanmar to Bangladesh since August 2017.

I’m back in #coxsbazar #Bangladesh this week reporting on the plight of #Rohingya #refugees for @AJEnglish … It was impressive today to see the massive efforts underway to relocate #refugee families who are at high risk of landslides pic.twitter.com/gEn5UZZDGk — Mohammed Jamjoom (@MIJamjoom) July 1, 2018

The Rohingya face discrimination in Myanmar, where they have been stripped of their citizenship.

A UN Security Council delegation visited Myanmar and Rakhine state in early May, meeting refugees who gave detailed accounts of killings, rape and villages torched at the hands of Myanmar’s military.

Myanmar has vehemently denied allegations by the US, the UN and others of ethnic cleansing.

Bangladesh and Myanmar agreed in November to begin repatriating the Rohingya but the process has stalled, with both sides accusing the other of frustrating the effort.

Fewer than 200 have been resettled, and the vast majority refuse to contemplate returning until their rights, citizenship and safety are guaranteed.

Around 100 Rohingya staged a protest just before Guterres’s visit, unhappy about a preliminary UN deal with Myanmar to assess conditions on the ground for their possible return home.

The United Nations has said that conditions in the persecuted minority’s home state of Rakhine in western Myanmar are not conducive to the refugees’ safe, voluntary and dignified repatriation.