The UN Special Representative in Haiti, Edmond Mulet, has warned of a sharp increase in lynchings and other mob attacks in the Caribbean nation.
Six people were killed in a single week in a number of attacks this month, the UN Stabilisation Mission in Haiti says.
Mr Mulet said he hoped the sharp rise would not be become a trend, in an interview with the Associated Press.
He blamed corruption in the legal system, saying people were fed up and taking justice into their own hands.
Lynchings have become more frequent in rural areas, where the police presence is thin and courts barely operate.
Mr Mulet, a Guatemalan diplomat who is also head of the UN mission, Minustah, said there had been a very large number of lynchings in recent months.
He said the rise was in part the result of a lack of confidence in Haiti's corrupt judicial system, which detains hundreds of people without trial while those who can afford to pay a bribe are released.
"You have cases of gang leaders being released after paying judges," he told the Associated Press on Friday.
"The population knows, so they're fed up... and they take justice into their hands."
Mr Mulet described one incident, where two men were mistaken for kidnappers and were beaten to death by a crowd of people armed with rocks and sticks.
Ten people were subsequently arrested, but only one has been imprisoned.
Mr Mulet said Minustah would launch a campaign to remind people lynchings were a crime and urge churches to denounce the practice.
The UN has a 9,000-strong peacekeeping force in place in Haiti.