The new UN human rights envoy for Myanmar has expressed serious concern about conditions in camps for more than 100,000 mostly minority Muslims displaced by violence led by Buddhist extremists, and has warned that the country's human rights situation may be deteriorating.

Yanghee Lee spoke on Saturday at the end of a 10-day fact-finding mission to Myanmar, her first in the capacity of UN rapporteur.

She said Myanmar should be applauded for having come a long way since installing an elected government in 2011 after almost five decades of repressive military rule.

"Yet, there are worrying signs of possible backtracking, which if unchecked could undermine Myanmar's efforts to become a responsible member of the international community that respects and protects human rights," she said, after talks with political and social leaders and trips to troubled areas of the country.

Lee visited western Rakhine state, where since 2012, violence between Rakhine Buddhists and Rohingya Muslims has left at least 280 people dead and 140,000 homeless, mostly Muslims confined in squalid camps.

"The situation is deplorable," she said, reading to reporters from a 10-page statement.

'Systematic discrimination'

She said she believed camp residents did not have adequate access to basic services and had heard "disturbing reports" of people dying in the camps due to the lack of emergency medical care and failure to adequately treat preventable illnesses and pregnancy-related conditions.

"By virtue of their legal status (or lack of), the Muslim community has faced and continues to face systematic discrimination, which include restrictions in the freedom of movement, restrictions in access to land, food, water, education and health care, and restrictions on marriages and birth registration," Lee said.

She added she was concerned that "the government's plan for long-term peaceful co-existence may likely result in a permanent segregation" of the Buddhist and Muslim communities.

Lee called for a law banning hate speech, saying she was concerned by its spread "and incitement to violence, discrimination and hostility in the media and on the internet, which have fuelled and triggered further violence."

She also called for the withdrawal of a legislative package on the so-called protection of race and religion that would limit the civil rights of the Muslim community.