Three men have been arrested in connection with the claim of responsibility made following the gun attack on a PSNI officer in February.
Detective Chief Inspector John Caldwell was seriously injured in a shooting outside a sports complex in Omagh, Co Tyrone.
The men, aged 23, 25 and 36, were arrested in Derry today under the Terrorism Act.
They have been taken to Musgrave Serious Crime Suite in Belfast for questioning.
