Dissident republicans are believed to have been responsible for a bomb attack on the headquarters of the Police Service of Northern Ireland.
A bomb was discovered at the premises in Dundonald House on the Stormont Estate in east Belfast yesterday. It was defused by British army experts, who described it as a "crude, anti-personnel device".
Forensic experts also removed several other items from the scene for further examination. A caller to a local newsroom claimed the bomb had been planted by the "Real IRA" to highlight its campaign for segregation in Maghaberry Prison, Co Antrim.
Republican and loyalist prisoners are housed together in the jail and republicans have complained they are in danger. A prison service spokesman condemned the incident.
"This type of indiscriminate attack, which places the lives of anyone handling such a package at risk from serious injury or worse, is to be utterly condemned," he said.
Meanwhile, police were last night investigating reports of a suspicious object at the doorway of a house in Carmeen Drive, Newtownabbey, Co Antrim. It is said to be the home of a loyalist, Mr Sammy Duddy.
He is a member of the Ulster Political Research Group, which advises the UDA. The incident is understood to be part of the ongoing internal feud between the mainstream UDA and Johnny Adair's "C Company".
Adair's supporters have been blamed for pipe-bomb attacks on two bars and a club in north and west Belfast on Wednesday night.
Adair was returned to prison earlier this month as violence intensified in the feud. In one incident on Wednesday, a pipe-bomb was hurled at the door of McKenna's pub on the upper Crumlin Road in the Ballysillan area.
The device blew the tiles off the steps of the premises. Seven people were inside but no-one was injured.
In a second incident, a woman was left shocked after a device was thrown at the Cavehill Inn on the Cavehill Road. A window shutter was damaged. Police said there could have been casualties if the shutter had not been in place.
British army bomb experts also made safe a device left outside a social club on the Shankill Road in Belfast.