A human rights watchdog says Iraq has executed 31 men for their alleged role in the 2014 mass killing of hundreds of Iraqi army cadets by the Islamic State group.

Amnesty International said in a statement Tuesday night that the executions took place on Friday, citing local officials in Salahuddin province, where the bodies transferred to be collected by their families.

The London-based watchdog said the execution "is further proof of the Iraqi authority's blatant disregard for human rights and misguided use of the death penalty in the name of security."

It says the men's "confessions" were extracted under serious allegations of torture and they were convicted following deeply flawed and speedy trials

Requests for comments from the Judicial Council and Justice Ministry were not immediately answered.