A Myanmar rights group has claimed it had to cancel the public launch of a report on alleged army torture and war crimes after two hotels backed down from agreeing to host the event.

The Ta’ang Women’s Organisation (TWO) blamed the regional government for forcing the the hotels in Yangon, the former capital – also known as Rangoon – to drop plans to host a press conference this week.

“The Yangon government blocked it,” the organisation said in an email.

The report, seen by the Guardian, highlighted what it said were “systematic war crimes” in Ta’ang areas of northern Shan state over the past five years, committed by the armed forces, or Tatmadaw, who are fighting a decades-old insurgency.

The study documented torture of more than 100 civilians in 33 villages, who were accused of fighting with resistance forces.

“Villagers were usually tied up with rope, kicked and beaten with guns. Other torture methods included suffocation with plastic bags, pouring petrol down throats, stabbing with knives, burning, and slicing skin off villagers’ arms,” the report said.

It added that extrajudicial killing, sexual violence and shelling of civilian targets had been carried out.

“TWO regards the cancellations by both hotels as an indicator of the ongoing restrictions on freedom of expression and media freedom, even under the new government,” the group said.

Aung San Suu Kyi, a former democracy campaigner who finally wrested executive powers from the military during a landmark election last year, has inherited a government in which the army retains significant power.

The Nobel laureate has promised to place national reconciliation at the forefront of her administration, but the country remains marred by long-running insurgencies along its border. Criticism of the army, once an imprisonable offence, is still often considered taboo.

Ethnic minorities such as the Ta’ang make up about 40% of modern-day Myanmar, and complaints are common of discrimination and a lack of services in border regions compared with the dominant Bamar population.

The Ta’ang National Liberation Army, an insurgent faction from Shan state, is also accused of abuses during years of conflict. The TNLA was excluded from the outgoing military-aligned government’s ceasefire agreement, signed last year. Since then, fighting has intensified, even after Suu Kyi formed a government in April.

TWO made an urgent call for Suu Kyi’s party, the National League for Democracy, to halt all Tatmadaw skirmishes across the country and begin a new peace process, “in which all ethnic resistance forces can take part in genuine political dialogue.”

“After the NLD won the 2015 election, we hoped they would end the offensives in the ethnic areas, but the attacks and war crimes have continued,” said Lway Poe Ngeal, the main author of the report. “It is clear the Tatmadaw still has absolute power and is above the law.”

Neither Yangon nor national authorities could be reached for comment on the cancelled events. The Tatmadaw could not be reached for comment.

However, the local Myanmar Times spoke to the manager of the Orchid hotel, the first venue to cancel the event, who said it accepted the booking but later backed out due to sensitivity.

“We agreed to the Ta’ang booking, but later we saw their invitation letter, which wrote too boldly about the military doing bad things. The issue was too big and too sensitive. We don’t want to make problems during the new government’s transition period so we cancelled the booking,” the Myanmar Times quoted the manger as saying.

The second hotel, the Excel, was quoted as saying it had not received permission to host the event.