First Minister Peter Robinson has accused Sinn Fein of attempting to blackmail the police over the arrest of Gerry Adams.
The party leader is undergoing a fourth day of questioning by detectives over the 1972 murder of Belfast mother-of-10 Jean McConville. Extra time granted to police to question him will expire later today.
Amid a growing row over the arrest, Deputy First Minister Martin McGuinness has warned his republican party will review their support for policing if Mr Adams is charged.
Martin McGuinness blamed an "embittered rump" left over from before the reform of policing whom he claimed wanted to destroy the peace process.
Mr Adams (65) was held by police on Wednesday - quizzed in relation to the 1972 IRA abduction and murder of Mrs McConville.
He has always denied any involvement in the killing.
The arrest has sparked huge global media attention on Thursday, with news of his detention making front pages across the world.
A raft of media remain camped outside Antrim police station on Sunday, where Adams remains in custody.
Belfast woman Jean McConville was seized by the IRA from her Divis Flats home in west Belfast, shot dead and secretly buried. Her body was found in 2003 on a Co Louth beach.
Speaking this week, Jean McConville's son Michael said he told police he would not identify the men who dragged his screaming mother from her home more than 40 years ago, for fear of reprisal.
"Everybody thinks that the IRA has gone away but they have not. If we tell we will be shot," he said.
On Thursday, Martin McGuinness blamed what he said was the "dark side" of policing for Gerry Adams' detention during the election campaign
After decades without significant developments in the criminal investigation, there have now been several arrests in connection with the killing of Jean McConville.
In March, republican - 77-year-old Ivor Bell - was charged in connection with the killing.
Bell - from Ramoan Gardens in west Belfast - faces counts of aiding and abetting the murder and of IRA membership.
His lawyer has said he will contest the charges.
Jean McConville was shot in the back of the head and buried just 50 miles from her home.
The IRA did not admit her murder until 1999.
In a statement on Wednesday, Gerry Adams once again denied having any involvement in one of the most high-profile killings of the Troubles.
Timeline of events
1972: Mrs McConville is dragged screaming from her home in Divis flats in west Belfast by an IRA gang of around 12 men and women. It is the last time her children see her alive. She is shot in the back of the head and secretly buried, so becoming one of the 'Disappeared' victims of the Troubles. In the 42 years since no one has been charged with her murder.
1999: One year after the signing of the historic Good Friday peace accord in Northern Ireland, the IRA finally admits responsibility for killing the 37-year-old widow, claiming she was an informer for the British Army.
The Independent Commission for the Location of Victims' Remains is set up by the British and Irish governments and the IRA passes on information on Mrs McConville's possible whereabouts on a stretch of coastline in Co Louth. But subsequent searches by the Irish police fail to find her body.
2001: Academics, historians and journalists embark on a five-year project to collate an oral history of the Northern Ireland Troubles. The Boston College initiative involves interviewing former paramilitaries about their roles in the conflict on the understanding their accounts would not be made public until they die.
2003: The body of Mrs McConville is finally found by a dog walker on Shilling beach in Co Louth after a heavy storm exposes her remains.
2006: An investigation by Northern Ireland's then police ombudsman Nuala O'Loan rejects the IRA claim that Mrs McConville was an informer.
2008: Brendan Hughes, a former IRA commander in Belfast who was one of the figures interviewed for the Boston College project, dies.
2010: A book containing excerpts from Hughes's interviews is published. Among claims outlined in Voices from the Grave is the allegation that Gerry Adams ordered the murder of Mrs McConville. Mr Adams emphatically rejects the accusation.
In the same year Dolours Price, who was convicted of the IRA's bombing of the Old Bailey in 1973, makes similar allegations about Mr Adams. Price indicates that she has also spoken to researchers at Boston College.
Mr Adams again denies the claims and highlights both Price and Hughes' criticism of his and Sinn Fein's involvement in the peace process.
2011: The Police Service of Northern Ireland (PSNI) launches a legal bid in the US to try to obtain tapes within the Boston College archive that relate to the murder of Mrs McConville.
2013: Dolours Price dies in her Dublin home of a suspected overdose of prescription drugs.
Later in the year the PSNI wins it lengthy court battle with Boston College and a number of the tapes are handed over.
Veteran republican Ivor Bell, 77, from Ramoan Gardens in west Belfast, is arrested and charged with aiding and abetting the murder of Mrs McConville and IRA membership. His lawyer tells a court that the prosecution case against his client is based on an interview he allegedly gave to the Boston College project. The solicitor insists Bell will fight the charges.
Mr Adams, in response to the renewed focus on the McConville case in the wake of Bell's charges, issues a statement indicating he is willing to speak to the officers investigating the case. He again refutes any suggestion he had anything to do with the crime.
At different junctures through March and April, four women and one man, with ages ranging from 56 to 60, are also arrested and questioned about the murder. All five were subsequently released but police are preparing reports on the four women for the Public Prosecution Service to assess.
Mr Adams, after back and forth contacts between his lawyer and detectives, presents himself at Antrim police station for interview. He is immediately arrested and taken into custody - a move that Sinn Fein brands unnecessary and an example of "political policing".