Six men who were arrested in Derry after a republican rally there yesterday have been released without charge.
The six were taken to the Antrim Serious Crime Suite for questioning.
At the ceremony at a cemetery in the city, dissident republican group the Real IRA vowed to continue to mount attacks on the security forces in Northern Ireland.
After wreaths were laid at a republican plot in the graveyard, a masked man read a statement, claiming that the Real IRA would continue the attacks.
He said British interests and infrastructure would be targeted.
The man claimed there was only one IRA and said there would be more violence in Northern Ireland.
A police helicopter monitored the rally, which was organised by the 32 County Sovereignty Movement.
Similar threats - to kill police officers - were made by a man in paramilitary uniform at the event last Easter.
That came less than a month after PSNI Constable Ronan Kerr was killed in a bomb blast in Omagh.
The Real IRA has claimed responsibility for the murders of two British soldiers at Massereene Barracks in Antrim in March 2009.
Earlier this month, two men were convicted of murdering Constable Stephen Carroll in March 2009.
His killing was claimed by the Continuity IRA.
