A dissident republican bomb discovered outside Newry, County Down last week contained 600 pounds of explosives.
It has also been revealed that the bomb was twice the size as the device that exploded outside Newry courthouse two years ago.
On Thursday, the viable bomb was discovered. It was made safe on Friday.
However, the PSNI were criticized for letting motorists drive by the device before closing off the road.
Last month, the PSNI were also criticized after taking over an hour to arrive at a bomb alert, also in Newry. On that occasion, residents had to use their own vehicles to block the road off before police arrived.
Speaking at the weekend, Chief Superintendent Alasdair Robinson said: "If this had exploded it would have caused devastation.
"To put it in perspective - anyone within 50 meters of this device would have been killed and anyone within 100 meters seriously injured."
Rejecting criticism that motorists had been able to drive past the bomb he said police had closed a main cross-border road within 12 minutes.
"Many police services would struggle to get an international border road closed in this time frame," he said.
"There was some residual traffic following the closures and, while we made the public aware of the road closures and advised them to avoid the area, a few cars ignored our advice. We do everything in our power to protect human life."
Ulster Unionist MLA, Danny Kennedy, said that if the bomb had exploded it would have caused serious destruction.
"It had the potential to cause lethal damage. A 600 pound device at the roadside waiting for a police patrol. It is just unthinkable," he said.
