She said that 3,040 Rohingya who attempted to flee by sea disembarked last year, primarily in Myanmar, Malaysia, Indonesia and Bangladesh. Nearly 45 per cent of those who did so were women and children.

"Most boats departed from Myanmar and Bangladesh, highlighting the growing sense of desperation amongst Rohingya in those two countries," Mantoo said.

"Those who have disembarked report that they undertook these dangerous sea journeys in an effort to find protection, security, family reunification, and livelihoods in other countries," she said.

"Among them are victims of trafficking, unaccompanied and separated children, and survivors of sexual- and gender-based violence."

A military crackdown in Myanmar in 2017 sent hundreds of thousands of Muslim-minority Rohingya fleeing into neighbouring Bangladesh with harrowing stories of murder, rape and arson.

Myanmar is facing genocide accusations at the UN's top court following the mass exodus.

Mantoo said calls by UNHCR to maritime authorities to rescue and disembark people in distress have gone unheeded, with many boats adrift for weeks.

"The current crisis in the Bay of Bengal and the Andaman Sea is a crisis of solidarity," she said.

UNHCR is calling for a full regional response, addressing human trafficking, search and rescue efforts and support in countries where Rohingya refugees disembark.

It also wants to see efforts to address the root causes of why Rohingya are fleeing Myanmar.

Mantoo said that without such a response, "more people will die on the high seas" as people undertake dangerous journeys in search of safety.