"We took the necessary measures in a timely manner on this file, a long time ago," Maliki said regarding the devices that Iraq had bought from a British businessman, according to a statement on his website.
Maliki said legal action has been taken against some of those involved in the case. "We will continue to follow this file in accordance with developments inside and outside Iraq," he added.
But despite the sentencing and overwhelming evidence that the devices are worthless, the Iraqi government has not taken them out of circulation, and security forces continue to use them at checkpoints.
"The device is a 100-per cent failure and we know that, but it is imposed on us; we cannot disobey direct orders," a policeman in Baghdad told AFP on Friday.
Relying on "bomb detectors" that do not work is an especially grave issue in Iraq, where violence is a major problem and bombings by militants are common.
More than 450 people were killed in violence in Iraq last month, according to AFP figures based on security and medical sources.