U.N. human rights officials are denouncing the execution of a man and his two wives in Iraq's Kurdish region over the kidnapping and murder of two girls, saying they fear the self-ruled region may slide back toward use of the death penalty.

The Office of the High Commissioner for Human Rights said Tuesday that Farhad Jaafar Mahmood and wives Khuncha Hassan Ismaeil and Berivan Haider Karim were hanged Aug. 12 following convictions in April last year.

The U.N. opposes the death penalty. The human rights office said the three executions are the first under the Kurdish regional government since an "informal moratorium" was set up there in 2008.

It said Iraq overall has executed more than 600 people since it reinstituted the death penalty in 2004 after Saddam Hussein's fall.