UN human rights officials have said it is likely that “crimes under international law” have been committed against the Rohingya in Myanmar and called for a body to collect evidence that could be presented in international criminal courts.

Speaking to the Human Rights Council on Monday, the UN special rapporteur on human rights in Myanmar, Yanghee Lee, said that “the repressive practices of previous military governments were returning as the norm once more” in Myanmar.

Lee gave the strongest call yet for accountability for the crimes committed in Rahkine since August 2017 that have driven more than 700,000 Rohingya over the border to Bangladesh. The campaign of violence by the military has seen thousands killed, Rohingya villages burned to the ground and hundreds of women raped and abused.

Lee called for the creation of an independent investigative body to “investigate, document, collect, consolidate, map, and analyse evidence of human rights violations and abuses”.

This “master database”, she said, could then be used as the basis to put the “individuals who gave the orders and carried out violations against individuals and entire ethnic and religious groups” on trial in international criminal courts or tribunals.

“The government leadership who did nothing to intervene, stop, or condemn these acts must also be held accountable,” added Lee. Much of the international focus has been on the role of Aung San Suu Kyi in the campaign of violence. Speaking to reporters, Lee said that “complicity is a very serious issue” but added that she had a “little element of hope” that the Nobel peace prize winner “will put her foot down and say once and for all let’s stop this”.

The three experts of the UN fact-finding mission on Myanmar, who also addressed the human rights council about their ongoing investigation, were equally forthright in their condemnation.

The evidence they had collected “points at human rights violations of the most serious kind, in all likelihood amounting to crimes under international law”.

The UN has been denied access to Rahkine since late last year, so both Lee and the fact-finding mission have been forced to conduct their investigations in Cox’s Bazaar in Bangladesh, where hundreds of thousands of Rohingya are now living in refugee camps.

Chair of the fact-finding mission, Marzuki Darusman, the former Indonesian attorney general, said the Myanmar government’s continued denial of any culpability for the violence in Rahkine was “untenable”.

Just last week the Myanmar military released a lengthy denial stating that the Rohingya – who they refer to as “illegal Bengalis”– had burned down their own villages and that their own investigation had concluded “security personnel did not commit extrajudicial killings or sexually abuse and rape women. There was no unlawful detention of people, beating, killing and arson as well.”

But Darusman said they had “hundreds of credible accounts of the most harrowing nature” including corroborated evidence of brutal gang rapes, sexual violence against women and the killing of babies and children.

“People died from gunshot wounds, often due to indiscriminate shooting at fleeing villagers. Some were burned alive in their homes – often the elderly, disabled and young children. Others were hacked to death,” the experts told the human rights council.

• This article was amended on 12 November 2018 because an earlier version misspelled Yanghee Lee’s name as Yee. This has been corrected.