SITTWE, Myanmar—Human Rights Watch says Myanmar forces failed to intervene as sectarian violence erupted last month in western Myanmar and then opened fire on Muslim Rohingyas as they tried to save their burning homes.

A 56-page report released Wednesday by the New York-based rights group called for strong international reaction to "atrocities" committed during last month's bloody unrest between Rakhine Buddhists and Muslim Rohingya.

The report was released just as a U.N. human rights envoy visited the area to investigate the conflict that left at least 78 people dead and about 100,000 homeless.

It says the conflict in Rakhine state shows that "state-sponsored persecution and discrimination persist" in Myanmar. It urged the international community not to be "blinded by a romantic narrative of sweeping change" in the country.