COX'S BAZAR, Bangladesh (AP) — U.N. Secretary General Antonio Guterres said Monday that he heard "unimaginable accounts of killing and rape" from Rohingya refugees who have fled from Myanmar to Bangladesh since last August to escape violence.

Guterres said in a tweet Monday after visiting sprawling refugee camps in Bangladesh's Cox's Bazar district that the hundreds of thousands of Rohingya Muslims who have taken shelter there want "justice and a safe return home."

Guterres was visiting Bangladesh to meet refugees who have been seeking protection from the United Nations and the international community.

He said at a news conference that the refugees had to live under terrible conditions in the camps because of massive violations of their human rights in Myanmar. He praised Bangladesh's government for being generous toward the refugees.

"It is impossible to visit these camps without breaking our hearts," Guterres said. "It is possibly one of the most tragic stories in relation to ... systematic violation of human rights."

He said the solidarity the international community was demonstrating toward the crisis was not necessarily being translated into reality when it comes to funding. Guterres said he was particularly worried about the potential threats of flooding and mudslides because of monsoon rains and urged the international community to step up with funding.

On Sunday, Guterres met Bangladeshi Prime Minister Sheikh Hasina and assured her of the U.N.'s continuing support for the Rohingya.

World Bank Group President Jim Yong Kim and United Nations High Commissioner for Refugees Filippo Grandi also visited the camps.

"I am extremely humbled and moved by the courage of the Rohingya," Kim said. "We cannot turn our heads away. We stand in solidarity. ... Today we are all Rohingya."

Kim promised to continue to work with Bangladesh's government to support the refugees. Prior to Kim's visit to Bangladesh, the World Bank announced a $480 million grant to Bangladesh to address the needs of Rohingya, including health care, education, water, sanitation and social protection.

Maulana Salamat Ullah, a refugee, told The Associated Press that he talked to Guterres and shared his thoughts of going back home.

"I told him we don't have our country, please help us take back our country. I am requesting the entire world to help get us our country back," he said.

"What would be our children's future? How will they get educated? We don't know what will happen," he said.

The recent spasm of violence in Myanmar began when Rohingya insurgents staged a series of attacks on Aug. 25 on about 30 security outposts and other targets. In a subsequent crackdown described by U.N. and U.S. officials as "ethnic cleansing," Myanmar security forces have been accused of rape, killing, torture and the burning of Rohingya homes. Thousands are believed to have been killed.

Rohingya are denied citizenship in overwhelmingly Buddhist Myanmar, where they've faced persecution for decades. They're derided as "Bengalis," and many in Myanmar believe they are illegal migrants from Bangladesh.

Bangladesh and Myanmar signed an agreement in November to start repatriating the Rohingya in January, but the process has been delayed over safety concerns and a complicated verification process. Global human rights groups and the U.N. said the conditions in Myanmar were not safe for the refugees' return.

The U.N. refugee agency and Bangladesh finalized a memorandum of understanding this year that said the repatriation process must be "safe, voluntary and dignified in line with international standards."