As many as 95 people are thought to have been executed in Iran this year.
The dramatic rise in the use of the death penalty has dashed hopes for human rights reform under President Hassan Rohani, the United Nations said earlier this year.
President Rohani won a surprise election last year, after pledging more openness with the West.
In September, the country released dozens of political prisoners, prompting hopes Iran would improve their human rights record.
"There were some encouraging signs last year where political prisoners were released ... But it appears at least in the past seven weeks that in fact executions have been scaled up," UN human rights spokeswoman Ravina Shamdasani told a news briefing.
"We regret that the new government has not changed its approach to the death penalty and continues to impose capital punishment for a wide range of offences. We urge the government to immediately halt executions and to institute a moratorium."
Last year Iran executed between 500 and 625 people, including at least 28 women and two children, Ms Shamdasani said.
- Daily Mail