Rohingya refugees who fled violence in Myanmar have told how government forces gang-raped women, slit people’s throats and threw children into burning houses, a UN envoy has said after a mission to neighbouring Bangladesh.

Yanghee Lee said the accounts given by Rohingya who had crossed into Bangladesh since a crackdown across the border in October indicated the violence was “far more extensive” than she had previously realised.

“There was not a single account I heard which was not harrowing,” said the human rights observer in a statement after her four-day visit to Bangladesh ended on Friday.

“I was especially affected by a mother who repeatedly expressed regret for mistakenly thinking that her son had been brought out from their burning house.

“She heard him screaming for her and managed to save his life but burn scars have been seared onto him — scars which I saw with my own eyes.”

Lee said she heard “allegation after allegation” of horrific events, including the slitting of throats, houses being set alight with people tied up inside and very young children thrown into the fire.

Almost 73,000 Rohingya have arrived in Bangladesh since the military unleashed a four-month campaign of violence in Myanmar’s Rakhine state which the UN has said may amount to crimes against humanity.

The Rohingya are a stateless, mainly Muslim minority who have long suffered discrimination in predominately Buddhist Myanmar, where many people consider them illegal immigrants.

Most of the refugees are now living in squalid camps in Bangladesh’s Cox’s Bazar district which borders Rakhine.

Myanmar says its operations, which began last October, were aimed at tracking down militants who attacked police border posts in Rakhine and have now ended.

The country’s de facto leader Aung San Suu Kyi, a Nobel peace laureate, has faced criticism for failing to act against the crackdown.

Lee accused Myanmar of continued discrimination and urged authorities there to act to prevent further rights abuses, and investigate those already alleged to have occurred.

Bangladeshi authorities estimate 400,000 Rohingya refugees are now living in Bangladesh, including the most recent arrivals.

The Dhaka government has approved a controversial plan for their relocation to an island.