Gardaí investigating the murder of a 32-year-old man in Dublin yesterday have set up a number of armed checkpoints in the city.
There are concerns that there could be retaliation for the killing of Alan Ryan, who was shot dead on Grange Lodge Avenue in Clongriffin.
Expressions of sympathy were published on a website this morning claiming to represent the Derry 32 County Sovereignty Committee.
Ryan, who was from Grange Abbey Drive in Donaghmede, had served jail terms for IRA activities and gun possession.
Detectives believe he was recently involved with a Real IRA group that was in conflict with a Dublin drugs gang.
Gardaí have set up armed checkpoints and increased patrols around the area.
They say his murder will be fully investigated and have renewed their appeal for witnesses or anyone with information to contact them in confidence.