A senior police officer has defended the PSNI's handing of a security alert in Newry, which led to the discovery of a 500lb bomb.
The PSNI were criticised after hundreds of motorists drove past the van containing the bomb after cones cordoning it off were removed.
Chief Superintendent Alasdair Robinson said a full cordon was put in place when the suspect vehicle was located.
He said police were hampered by two "ambiguous" bomb warnings.
Mr Robinson said they had hindered their search for the bomb.
"The warning came in to a local charity and it said the following: 'This is the IRA, there is a bomb under the underpass'," he said.
"No location was given and there was nine seconds of recording.
"The previous one, the first one said: 'This is the IRA, we've planted a bomb on the underpass at the Berliss Road and it is to go off in 45 minutes'.
"Now there is no Berliss Road on the M1. The M1 goes from Belfast to the west.
"The M1 of course, is the A1 / M1 which is the national north south route, so that was the level of ambiguity."
He said police did not at that stage know where the bomb was.
"It wasn't until almost an hour later that we could confirm that we had a suspect vehicle. At that point, we put a full cordon in place," he added.
Police cordon breached
"We closed the roads, both with police and the Roads Service, who kindly helped us with that. We had the whole scene completely secure and locked down for the evening."
Chief Superintendent Robinson said some members of the public had "breached" the police cordon.
"You can't blame all of the people who drove past because they came to what they thought was an open road," he said.
"We checked the cordon and we put police back in to close them down."
He said the PSNI would review their use of signage.
"It is not part of anyone's plan to allow any member of the public to go anywhere near what was a suspect device.
"Sophisticated and substantial"
"The police were on the ground but as far as we were concerned the cordon was complete."
Police said the bomb, which was left on the Belfast to Dublin road, was "sophisticated and substantial".
The Secretary of State Owen Paterson said the community was "fed up" with the recent spate of alerts and condemned the incident.
However, he refused to be drawn on how the police dealt with the bomb and said police handling of the security alert was an "operational matter."
"There are questions that need to be answered and I will put them to the chief constable and the justice minister when I meet with them next week," Mr Paterson said.
"I am not going to comment until I have spoken to them."
Acting Policing Board chairman Brian Rea said the police had done all they could to make the area safe.
"I had a briefing on Sunday from the district commander in the area who reassured me they were doing all in their power to keep that road closed," he said.
"The police operate in that area under a constant threat. We have heard in the past where a device has been planted as a come on or trap.
"Police have to be extremely careful when they enter into this type of situation and often they have to leave it some time before it is safe for them to do so."
The alert, which started on Thursday night, was less than a week since the murder of PSNI constable Ronan Kerr in Omagh, County Tyrone.
Police believe that the van containing the bomb was abandoned in the underpass because of increased police activity in the wake of the murder last Saturday.
Army bomb experts carried out several controlled explosions on the vehicle on Friday night.