Myanmar's military junta has been accused of forcing people to the brink of starvation with repeated offensives since it took power in a coup earlier this year.
The Special Advisory Council for Myanmar said the junta had destroyed food supplies and killed livestock while cutting off roads used to bring in food and medicine.
The council said military offensives in the country's north-west and east have prevented farmers from harvesting their crops.
The UN said that the international community should work with the parallel national unity government NUG set up by pro-democracy politicians to get support for people.
Chris Sidoti, former member of the UN fact-finding mission, said: Instead of wringing hands wondering what to do, the international community can and must work together with the NUG to get help across borders into the country and to the people who need it.
There are trusted local humanitarian and medical networks, including service providers and community-based and civil society organisations that are already helping people. They need to be supported and empowered. The council has accused the junta of crimes against humanity, including intentionally depriving people of food.
Yanghee Lee, the former UN envoy to Myanmar, said it was important that the junta continued to be spurned internationally because of the impact of its actions.
Lee said that anyone who tries to accommodate the military in the interests of the people is only prolonging their suffering. These actions can be viewed as being complicit in military crimes. Since the February coup, more than 600,000 people have been internally displaced, with more than 600,000 in the country as of November, according to a UN emergency update. The report said that most internally displaced people and host communities were struggling for food, medicine and fuel.
In Myanmar, about 3 million people need life-saving assistance, and 2 million of them have been identified since the coup, according to the UN.