The Real IRA has threatened violence during a visit by the Queen to the Irish Republic next month.
In a statement issued to mark the anniversary of the 1916 Easter Rising, the dissident republican group said police officers would be targeted ''regardless of their religion, cultural background or motivation''.
The statement also said: The Queen of England is wanted for war crimes in Ireland and is not wanted on Irish soil.
The Real IRA killed two soldiers in Antrim two years ago, and last year exploded a car bomb in Derry. It also claimed responsibility for the Omagh bomb in 1998.
The Queen's visit will be the first by a British monarch since Ireland gained its independence from Britain in 1921.