Authorities in Myanmar aided the killing of Rohingya Muslims last year, according to Human Rights Watch.
In a new report into the unrest, the organisation said security forces either stood by or joined in as Rakhine Buddhist mobs went on the rampage, slaughtering men, women and children between June and October.
Human Rights Watch has also condemned the EU’s moves to lift all but its arms embargoes.
Phil Robertson, Deputy Asia Director at HRW, said: “The EU steps are premature and unfortunate, since it will diminish the EU’s leverage with the Burmese government. Essentially, in our view, the EU member countries are ditching measures that have motivated the current progress on human rights.”
The report into the Rakhine state violence, which called for international pressure on the government, said authorities had blocked aid from going into the squalid camps occupied by stateless Rohingya and Kaman Muslims, exposing them to malnourishment and diseases such as cholera or typhoid.
More than 120,000 people fled arson and machete attacks in Rakhine state and thousands have embarked on perilous journeys to other countries, where they are prey to human trafficking gangs.
An estimated 800,000 stateless Rohingyas live in Myanmar, where the authorities restrict their movements and access to employment and consider them illegal immigrants from Bangladesh.