The New IRA has admitted responsibility for the murder of journalist Lyra McKee in Londonderry, as police made a new arrest.
Miss McKee, 29, died as a result of injuries sustained when she was shot on the Creggan estate on April 18.
In a statement given to The Irish News using a recognised code word, the group offered “full and sincere apologies” to her family and friends.
It came as a 57-year-old woman was arrested under the Terrorism Act in connection with Ms McKee’s death.
In a short statement, the PSNI did not disclose any further details about the nature of the arrest, only that she had been taken to Musgrave Serious Crime Suite.
Two teenage men initially arrested by detectives investigating the murder were later released without charge.
The New IRA is an amalgam of armed groups opposed to the peace process and it recently claimed responsibility for parcel bombs sent to London and Glasgow in March.
Police believe the violence was orchestrated in response to an earlier search by officers aimed at averting imminent trouble associated with this week’s anniversary of the Easter Rising.
The statement said: “On Thursday night, following an incursion on the Creggan by heavily armed British crown forces which provoked rioting, the IRA deployed our volunteers to engage.
“We have instructed our volunteers to take the utmost care in future when engaging the enemy, and put in place measures to help ensure this.
“In the course of attacking the enemy Lyra McKee was tragically killed while standing beside enemy forces.
“The IRA offer our full and sincere apologies to the partner, family and friends of Lyra McKee for her death.”
SDLP leader Colum Eastwood said the statement was an absolute disgrace, that showed no remorse for the death of Ms McKee.
“Their so-called instruction to their ‘volunteers’ to ‘take the utmost care’ when engaging in violence is utterly sickening and devoid of any humanity,” he said.
“They must recognise the glaringly obvious fact they are not wanted by the people of the North. It is time to disband.
“The murder of Lyra McKee must not be in vain. Together, political leaders must come together to re-engage in a talks process to fill the vacuum that currently gives groups like this too much oxygen.”
Alliance Party leader Naomi Long said: “First, their spokespeople dismissed Lyra McKee’s murder as an “accident”. Now, the New IRA accept responsibility for her murder, while asking their members to be more careful when trying to murder people in future.
“To be clear, killing a police officer is every bit as wrong as killing a journalist. Both are there doing their job. Both of them have families who care about them. Neither deserve to be shot in cold blood.
With every statement they merely expose themselves further.”
The admission comes as police in Northern Ireland say the investigation into the killing is continuing at a “rapid pace”.
Detective Superintendent Jason Murphy said more than 140 people had contacted officers with information, adding: “This was an attack on the community. Lyra, tragically, was a random victim and I need the public to continue to support us.
“Many witnesses have contacted us to give us information that has been provided to them.
“More than 140 people have contacted us via our MIPP (Major Incident Public Portal) with messages, including mobile phone footage.”
Mr Murphy appealed for witnesses or anyone with information to come forward.