One of the five men arrested yesterday in connection with the murder of Constable Ronan Kerr last April has been released without charge.
A woman was arrested earlier today by detectives investigating Mr Kerr's murder.
The suspect (23) joins the four men already being questioned as part of a major security operation that involved around 200 officers.
Constable Ronan Kerr (25) a Catholic member of the Police Service of Northern Ireland, was killed when a booby-trap bomb exploded under his car outside his home in Omagh, Co Tyrone, on April 2nd.
The woman was arrested in Omagh this morning.
Police have confirmed the arrests were connected to the murder and associated incidents.
Searches were also carried out in Coalisland, Co Tyrone, and Toome, Co Antrim, as well as Bellaghy and Ballyronan, south Derry. Today, more searches are being carried out in Omagh.
The suspects were arrested under the Terrorism Act and taken to the Serious Crime Suite at Antrim police station for questioning, a police spokesman confirmed.
A number of items were seized during the police searches including clothing, mobile phones, computers and vehicles. They have been removed for forensic examination and analysis.
A man aged 22 was detained in Coalisland. He is the man who has been released. Two men aged 27 and 46, were arrested in Toome, a 37-year-old was held in Bellaghy and a 33-year-old in Ballyronan.
The officer in charge of the investigation, Detective Superintendent Raymond Murray, said police were determined to pursue every possible line of inquiry.
A £50,000 reward remains on offer for information leading to the arrest and conviction of those responsible for Constable Kerr’s murder.
PA