A viable letter bomb has been posted to a senior police officer in Northern Ireland, it has been confirmed.
The package addressed to chief inspector Andy Lemon was intercepted at a sorting office in Strabane, Co Tyrone.
Mr Lemon, who is the area commander in Strabane, described it as a worrying development. Dissident republicans are being blamed for the attempted attack. The alarm was raised after postal workers at an office on Castle Street discovered a suspicious package.
A spokesman for the Police Service of Northern Ireland (PSNI) said it was a small viable device. He said: "It has been taken away for further examination."
Six roads around the sorting office were closed for several hours from about 10.15am as bomb squad officers carried out their investigations. The security alert has now ended and all roads in the area have been re-opened.
Sinn Fein MLA for Strabane, Michaela Boyle said lives were put at risk. She said: "There is no place in society for this sort of activity from these individuals. It could have been fatal."
The device, which has been described as crude, was made up of a battery pack and accelerant. It was packed into a brown envelope.
Mr Lemon said the vigilance of postal staff saved lives. "It could have gone up at any time," he said. "This was a very dangerous device and I would like to praise the Post Office staff for noticing it."
The envelope was addressed to Mr Lemon at Strabane police station. He added: "I do not believe this is a personal attack but more a general attack on the police. Because I am area commander, a lot of mail would come into the police station addressed to myself, but I do not open any of it... This was an attempt to kill or injure police."
Northern Ireland's First and Deputy First Ministers described the attack as calculated and callous. In a joint statement Peter Robinson and Martin McGuinness said: "The individuals behind this need to be brought to justice as actions like this have no place in society and those responsible have nothing positive to offer."