Human Rights Watch have accused Burmese security forces of committing widespread rape against women and girls as part of a campaign of ethnic cleansing during the past three months against Rohingya Muslims in the country's Rakhine state.

The allegation in a report by the New York-based rights group echoes an accusation by Pramila Patten, the UN special envoy on sexual violence in conflict, earlier this week. Patten said sexual violence was “being commanded, orchestrated and perpetrated by the Armed Forces of Burma.”

Burma's army released a report on Monday denying all allegations of rape and killings by security forces, days after replacing the general in charge of the operation that drove more than 600,000 Rohingya Muslims to flee to Bangladesh.

The United Nations has denounced the violence as a classic example of ethnic cleansing. The Burmese government has denied allegations of ethnic cleansing.

Human Rights Watch spoke to 52 Rohingya women and girls who fled to Bangladesh, 29 of whom said they had been raped. All but one of the rapes were gang rapes, Human Rights Watch said.

“Rape has been a prominent and devastating feature of the Burmese military's campaign of ethnic cleansing against the Rohingya,” said Skye Wheeler, women's rights emergencies researcher at Human Rights Watch and author of the report.

“The Burmese military's barbaric acts of violence have left countless women and girls brutally harmed and traumatised,” she said in a statement.

Human Rights Watch called on the UN Security Council to impose an arms embargo on Burma and targeted sanctions against military leaders responsible for human rights violations, including sexual violence.

The 15-member council last week urged the Burma government to “ensure no further excessive use of military force in Rakhine state.” It asked UN Secretary-General Antonio Guterres to report back in 30 days on the situation.

Burma has said the military clearance operation was necessary for national security after Rohingya militants attacked 30 security posts and an army base in Rakhine state on 25 August.

Burma is refusing entry to a UN panel that was tasked with investigating allegations of abuses after a smaller military counteroffensive launched in October 2016.

Rohingya refugees – in pictures Show all 15 1 /15 Rohingya refugees – in pictures Rohingya refugees – in pictures A young girl and a baby wade through mud after arriving in Whaikhyang, Bangladesh from Burma on 10 September Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya refugees walk through a camp in Whaikhyang, Bangladesh after arriving from Burma Dan Kitwood/Getty Images Rohingya refugees – in pictures A young Rohingya refugee gathers firewood after arriving in Whaikhyang, Bangladesh from Burma Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya refugees wait for sacks of rice to be distributed in Whaikhyang, Bangladesh Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya Muslim refugees arrive on a boat in Whaikhyang, Bangladesh after crossing from Burma on 8 September Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya Muslim refugees react after being re-united with each other after arriving in Whaikhyang, Bangladesh on a boat from Burma Getty Rohingya refugees – in pictures Rohingya Muslim refugees walk along the remains of a road after arriving in Whaikhyang, Bangladesh on a boat from Burma Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya Muslim refugees wade through water after arriving in Whaikhyang, Bangladesh by boat from Burma Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya Muslim refugees wade through water after arriving in Whaikhyang, Bangladesh by boat from Myanmar Dan Kitwood/Getty Images Rohingya refugees – in pictures Rohingya Muslim refugees stand in the rain after arriving in Whaikhyang, Bangladesh by boat from Burma Dan Kitwood/Getty Images Rohingya refugees – in pictures Indian children hold placards and shout slogans during a protest against the alleged persecution of the Rohingya Muslims in Burma EPA/Raminder Pal Singh Rohingya refugees – in pictures Supporters of the Difa-e-Pakistan Council (DPC), an Islamic organisation, listen to their leaders' speeches against Burma's persecution of Rohingya Muslims, during a demonstration in Karachi Reuters/Akhtar Soomro Rohingya refugees – in pictures Hundreds of Iranians take part in a protest against violence in Myanmar after weekly Friday prayers, in Tehran EPA/Abedin Taherkenareh Rohingya refugees – in pictures Indonesian Muslim activists hold placards and shout slogans during a protest against the alleged persecution of the Rohingya minority in Magelang, Central Java, Indonesia EPA/Ali Lutfi Rohingya refugees – in pictures Members of an Islamic organisation shout slogans against the Burma government during a protest in Dhaka, Bangladesh EPA

Hala Sadak, a 15-year-old from Hathi Para village in Maungdaw Township, told Human Rights Watch that soldiers had stripped her naked and then about 10 men raped her.

She told Human Rights Watch: “When my brother and sister came to get me, I was lying there on the ground, they thought I was dead.”