U.N. special envoy on human rights Tomas Ojea Quintana said he had serious concerns about renewed violence between Buddhists and Muslims in Myanmar.
Myanmar last month imposed curfews and states of emergency over parts of the country in response to religious violence. Human Rights Watch said at least 40 people died in the latest violence, which it said was similar to fighting last year in Rakhine.
Quintana said authorities need to take swift action to stop the violence from spreading. This includes working on issues of discrimination.
"The warning signs have been there since the communal violence in Rakhine state last June and the government has simply not done enough to address the spread of discrimination and prejudice against Muslim communities across the country," he said in a statement.
Myanmar earned recognition for political reforms that began with general elections in 2010. Rights groups said the lingering violence may undo most of that progress, however.