The UN human rights chief has condemned a recent spate of "horrific attacks" on people with albinism in Tanzania, including the murder of a young boy.
The government should act to stop the "vicious killings" and discrimination they faced, said Navi Pillay.
The mutilation and murder of people with albinism is often linked to witchcraft, the UN says.
Only five people have been convicted in Tanzania since 2000 for killing people with albinism, it adds.
Some 72 people have been killed in that time.
In 2009, President Jakaya Kiwete said the murders had brought shame to Tanzania and launched a national campaign to end the persecution of people with albinism.
'Arm hacked off'
In 2010, Salum Khalfani Bar'wani became the first person with albinism to be elected as an MP in Tanzania.
In a statement, Ms Pillay said four attacks on Tanzanians with albinism had been documented in just 16 days between the end of January and mid-February. They included:
- the murder of a seven-year-old boy, Lugolola Bunzari, on 31 January at Kanunge village in the Tabora region. His attackers slashed his forehead, right arm and left shoulder, and chopped off his left arm just above the elbow. The boy's grandfather, aged 95, was also killed in the attack as he tried to protect his grandson;
- a seven-month-old baby, Makunga Baraka, narrowly escaped death on 5 February after armed men attacked his home in the Simiyu region. Villagers chased the attackers away and surrounded the house to protect him. The baby and his mother were taken to the police station the following morning and given temporary sanctuary;
- a 39-year-old woman Maria Chambanenge was attacked on 11 February by five armed men, allegedly including her husband, in Mkowe village in the Rukwa region. They hacked off her left arm while she was sleeping with two of her four children. The five suspects were subsequently arrested and the victim's arm recovered - their trial is reportedly under way
- a 10-year-old boy, Mwigulu Matonange, was attacked on his way home from school and his left arm chopped off above the elbow by two unidentified men in Msia village in Rukwa. Three men have been arrested in connection with the attack.
"These crimes are abhorrent. People with albinism have the right to start living, like anyone else, without fear of being killed or dismembered," Ms Pillay said.
Tanzania's authorities needed to step up efforts to bring the attackers to justice, she added.
Public awareness campaigns should also be launched to end the stigma associated with albinism, Ms Pillay said.
"I am deeply alarmed by the general discrimination and social exclusion many people with albinism suffer, as a result of their skin colour, not just in Tanzania but in other countries as well," she said.
Some witchdoctors say that magic charms are more powerful if they contain body parts from people with albinism - this has led to a lucrative criminal trade in these body parts.